Go to the Content / Assets section in the CMS (not the Images section!) and try to upload a .TIFF file as asset. This fails with a message that the internally detected type does not match the mime type of the file.
This is due to the fact that the class that does check the InputStream of the file does not take the type TIFF into account. The check is done here: org.hippoecm.frontend.editor.plugins.resource.ImageInfo#check
I can see two directions to solve it: if the bytes in the stream are not recognized, return true on the check. Or: extend the code so TIFF file steams are also recognized.