This error just started popping up. Any help / clue as to what may be causing this:
I don't recall being able to do anything to fix it; just have to ungroup the items and recreate the group.
I take it as in error internal to the way PTC manages groups.
I usually use groups to control large assembly family tables when many items are toggled, and see the message there, but I don't think the error is exclusive to groups within family tables.
Have you found a solution to this problem? I have the same message appears in my SKELETON. I believed I had found the FEATURE GROUP that were the problem, because the message disappeared in INSERT MODE. So I deleted and re-created FEATURES below. But the problem reappeared the next GROUP, so I deleted and re-created them too. But the message appears again !? It's really sucks because now, in with the new INSERT MODE FEATURES, no message, but it seems that the problem is transferred to the next group each time. I can not redo all of my groups and FEATURES SKELETON. The funniest is that the ID number remains the same in the message! I tried UNGROUP but it changes nothing.