Required compound field contentblocks is not always highlighted (red) correctly when saving document

When using the content-block plugin, if the document has the mandatory contentblock field, the field title is not always highlighted when invalidated

Reproduction path:
1. Build contentblocksdemo [A], with <forge.content-blocks.version>1.11.04</forge.content-blocks.version>

2. Add "required" value to the property "validation-rules" at nodes:

• /hippo:namespaces/contentblocksdemo/contentblocksdocument/hipposysedit:nodetype/hipposysedit:nodetype/contentblocks
• /hippo:namespaces/contentblocksdemo/imageblock/hipposysedit:nodetype/hipposysedit:nodetype/image
• /hippo:namespaces/contentblocksdemo/textblock/hipposysedit:nodetype/hipposysedit:nodetype/hippostd_html
• /hippo:namespaces/contentblocksdemo/videoblock/hipposysedit:nodetype/hipposysedit:nodetype/video

3. Create a new "contentblocksdocument"

4. Without adding content save the document, and see the title "Add New Content Item*" turn into red.

5. Add a videoblock

6. Without adding content into the videoblock, remove it.

7. Save the document, and see the title "Add New Content Item*" is not red.

Expected behaviour:
After saving the document in step 7, the title "Add New Content Item*" should still be highlighted red.

This issue relates to: https://issues.onehippo.com/browse/HIPPLUG-918

[A]: https://forge.onehippo.org/svn/content-blocks/demo/tags/content-blocks-demo-1.11.01/