I have a document set that consists of multiple documents. Each document has a unique content type.
If I create a document set, I can
edit properties for all except one of the documents on the Document Set Welcome Page.
In the case of that one document, the
view/edit properties buttons are disabled (they are enabled for the other documents). If I edit the welcome page, the
view/edit properties buttons for that one document become enabled. If I stop editing the page, the
view/edit properties buttons for that one document become disabled.