Export of document with pdf gives an unusable yaml and broken file exports

Hippo 12.1 archetype
A document with only a title and a resource. resource is a pdf file.
Save and publish.
Go to console and yaml export on the handle.
Download zip.

Zip contains 6 pdf files, where 3 at most are expected (one per variant). Half the pdf files are corrupt.

This file will not import back into the repository. Fails with:

[INFO] [talledLocalContainer] org.apache.cxf.interceptor.Fault: Could not send Message.
[INFO] [talledLocalContainer] at org.apache.cxf.interceptor.MessageSenderInterceptor$MessageSenderEndingInterceptor.handleMessage(MessageSenderInterceptor.java:64) ~[cxf-core-3.1.14.jar:3.1.14]
[INFO] [talledLocalContainer] at org.apache.cxf.phase.PhaseInterceptorChain.doIntercept(PhaseInterceptorChain.java:308) [cxf-core-3.1.14.jar:3.1.14]
[INFO] [talledLocalContainer] at org.apache.cxf.jaxrs.client.AbstractClient.doRunInterceptorChain(AbstractClient.java:681) [cxf-rt-rs-client-3.1.14.jar:3.1.14]
[INFO] [talledLocalContainer] at org.apache.cxf.jaxrs.client.ClientProxyImpl.doChainedInvocation(ClientProxyImpl.java:781) [cxf-rt-rs-client-3.1.14.jar:3.1.14]
[INFO] [talledLocalContainer] at org.apache.cxf.jaxrs.client.ClientProxyImpl.invoke(ClientProxyImpl.java:235) [cxf-rt-rs-client-3.1.14.jar:3.1.14]
[INFO] [talledLocalContainer] at com.sun.proxy.$Proxy145.isAlive(Unknown Source) [?:?]
[INFO] [talledLocalContainer] at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[?:1.8.0_161]
[INFO] [talledLocalContainer] at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) ~[?:1.8.0_161]
[INFO] [talledLocalContainer] at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[?:1.8.0_161]
[INFO] [talledLocalContainer] at java.lang.reflect.Method.invoke(Method.java:498) ~[?:1.8.0_161]
[INFO] [talledLocalContainer] at org.apache.commons.proxy.ProxyFactory$ReflectionInvocation.proceed(ProxyFactory.java:236) [commons-proxy-1.0.jar:1.0]
[INFO] [talledLocalContainer] at org.hippoecm.frontend.service.restproxy.RestProxyServicePlugin$2.intercept(RestProxyServicePlugin.java:278) [hippo-cms-engine-5.1.0.jar:5.1.0]
[INFO] [talledLocalContainer] at org.apache.commons.proxy.ProxyFactory$InterceptorInvocationHandler.invoke(ProxyFactory.java:201) [commons-proxy-1.0.jar:1.0]
[INFO] [talledLocalContainer] at com.sun.proxy.$Proxy146.isAlive(Unknown Source) [?:?]
[INFO] [talledLocalContainer] at org.onehippo.cms7.channelmanager.restproxy.RestProxyServicesManager$2.run(RestProxyServicesManager.java:127) [hippo-addon-channel-manager-frontend-5.1.0.jar:5.1.0]
[INFO] [talledLocalContainer] at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:511) [?:1.8.0_161]
[INFO] [talledLocalContainer] at java.util.concurrent.FutureTask.run(FutureTask.java:266) [?:1.8.0_161]
[INFO] [talledLocalContainer] at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149) [?:1.8.0_161]
[INFO] [talledLocalContainer] at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624) [?:1.8.0_161]
[INFO] [talledLocalContainer] at java.lang.Thread.run(Thread.java:748) [?:1.8.0_161]
[INFO] [talledLocalContainer] Caused by: java.net.SocketException: SocketException invoking http://127.0.0.1:8443/site/_cmsrest/sites/_isAlive: Unexpected end of file from server
[INFO] [talledLocalContainer] at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method) ~[?:1.8.0_161]
[INFO] [talledLocalContainer] at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:62) ~[?:1.8.0_161]
[INFO] [talledLocalContainer] at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45) ~[?:1.8.0_161]
[INFO] [talledLocalContainer] at java.lang.reflect.Constructor.newInstance(Constructor.java:423) ~[?:1.8.0_161]
[INFO] [talledLocalContainer] at org.apache.cxf.transport.http.HTTPConduit$WrappedOutputStream.mapException(HTTPConduit.java:1390) ~[cxf-rt-transports-http-3.1.14.jar:3.1.14]
[INFO] [talledLocalContainer] at org.apache.cxf.transport.http.HTTPConduit$WrappedOutputStream.close(HTTPConduit.java:1374) ~[cxf-rt-transports-http-3.1.14.jar:3.1.14]
[INFO] [talledLocalContainer] at org.apache.cxf.transport.AbstractConduit.close(AbstractConduit.java:56) ~[cxf-core-3.1.14.jar:3.1.14]
[INFO] [talledLocalContainer] at org.apache.cxf.transport.http.HTTPConduit.close(HTTPConduit.java:658) ~[cxf-rt-transports-http-3.1.14.jar:3.1.14]
[INFO] [talledLocalContainer] at org.apache.cxf.interceptor.MessageSenderInterceptor$MessageSenderEndingInterceptor.handleMessage(MessageSenderInterceptor.java:62) ~[cxf-core-3.1.14.jar:3.1.14]
[INFO] [talledLocalContainer] ... 19 more
[INFO] [talledLocalContainer] Caused by: java.net.SocketException: Unexpected end of file from server
[INFO] [talledLocalContainer] at sun.net.www.http.HttpClient.parseHTTPHeader(HttpClient.java:851) ~[?:1.8.0_161]
[INFO] [talledLocalContainer] at sun.net.www.http.HttpClient.parseHTTP(HttpClient.java:678) ~[?:1.8.0_161]
[INFO] [talledLocalContainer] at sun.net.www.http.HttpClient.parseHTTPHeader(HttpClient.java:848) ~[?:1.8.0_161]
[INFO] [talledLocalContainer] at sun.net.www.http.HttpClient.parseHTTP(HttpClient.java:678) ~[?:1.8.0_161]
[INFO] [talledLocalContainer] at sun.net.www.protocol.http.HttpURLConnection.getInputStream0(HttpURLConnection.java:1587) ~[?:1.8.0_161]
[INFO] [talledLocalContainer] at sun.net.www.protocol.http.HttpURLConnection.getInputStream(HttpURLConnection.java:1492) ~[?:1.8.0_161]
[INFO] [talledLocalContainer] at java.net.HttpURLConnection.getResponseCode(HttpURLConnection.java:480) ~[?:1.8.0_161]
[INFO] [talledLocalContainer] at org.apache.cxf.transport.http.URLConnectionHTTPConduit$URLConnectionWrappedOutputStream$2.run(URLConnectionHTTPConduit.java:379) ~[cxf-rt-transports-http-3.1.14.jar:3.1.14]
[INFO] [talledLocalContainer] at org.apache.cxf.transport.http.URLConnectionHTTPConduit$URLConnectionWrappedOutputStream$2.run(URLConnectionHTTPConduit.java:375) ~[cxf-rt-transports-http-3.1.14.jar:3.1.14]
[INFO] [talledLocalContainer] at java.security.AccessController.doPrivileged(Native Method) ~[?:1.8.0_161]
[INFO] [talledLocalContainer] at org.apache.cxf.transport.http.URLConnectionHTTPConduit$URLConnectionWrappedOutputStream.getResponseCode(URLConnectionHTTPConduit.java:375) ~[cxf-rt-transports-http-3.1.14.jar:3.1.14]
[INFO] [talledLocalContainer] at org.apache.cxf.transport.http.HTTPConduit$WrappedOutputStream.doProcessResponseCode(HTTPConduit.java:1587) ~[cxf-rt-transports-http-3.1.14.jar:3.1.14]
[INFO] [talledLocalContainer] at org.apache.cxf.transport.http.HTTPConduit$WrappedOutputStream.handleResponseInternal(HTTPConduit.java:1616) ~[cxf-rt-transports-http-3.1.14.jar:3.1.14]
[INFO] [talledLocalContainer] at org.apache.cxf.transport.http.HTTPConduit$WrappedOutputStream.handleResponse(HTTPConduit.java:1560) ~[cxf-rt-transports-http-3.1.14.jar:3.1.14]
[INFO] [talledLocalContainer] at org.apache.cxf.transport.http.HTTPConduit$WrappedOutputStream.close(HTTPConduit.java:1361) ~[cxf-rt-transports-http-3.1.14.jar:3.1.14]
[INFO] [talledLocalContainer] at org.apache.cxf.transport.AbstractConduit.close(AbstractConduit.java:56) ~[cxf-core-3.1.14.jar:3.1.14]
[INFO] [talledLocalContainer] at org.apache.cxf.transport.http.HTTPConduit.close(HTTPConduit.java:658) ~[cxf-rt-transports-http-3.1.14.jar:3.1.14]
[INFO] [talledLocalContainer] at org.apache.cxf.interceptor.MessageSenderInterceptor$MessageSenderEndingInterceptor.handleMessage(MessageSenderInterceptor.java:62) ~[cxf-core-3.1.14.jar:3.1.14]
[INFO] [talledLocalContainer] ... 19 more