In XP7.7 we got the new allow-filter for parts. It is very nice. However, when starting to use it we experienced a few things that we didn’t expect, and that was a bit surprising at first leading is to research our code for bugs.
If you add an “allow”-rule for any specific content type, as was our need, it will effectively not be allowed on page templates or the
portal:sitecontent. That was unexpected even if we figured it out after a while. The docs should have a note on this as I think many will go through the same process as us here.
If a part is already on a page of the wrong type of content (as might be the case since this is a new feature) you will not get information about this in Content Studio. What you will get is a empty form, and no name of the part to the right. This led us first to research if our form was broken, or if there was any other bugs. After a while we discovered that we were on a disallowed content type. So, putting a tiny message into Content Studio on the right side would help a lot - “Part Xxx is not allowed on Content Type xxx and cannot be edited”.