Greetings.
First off, the bug report thread is linked in his signature (
this one), and he gets really grumpy when you don't use it
Now, however, let me tell you right there that this isn't a real bug afaik.
This is because the tooltip you mean (the one in your screenshot) is not for vassal opinion of the
liege, but of the
Pope.
However, in CK2Plus the bookmarks before 1066 by default have a united, Chalcedonian Christianity, which has the golden double-cross icon that is also visible in your screenshot.
And that version of Christianity does not have the Pope as religious head yet, which is why the tooltip says "Opinion of
No Character": The Pope does not exist yet (at least not as religious head), so the vassals can't have an opinion of him!
And thus the UI is "missing", because vanilla doesn't have this situation, and we don't have enough control over the UI to turn this off.
So nothing we can do about it really, but it's not a bug and doesn't affect gameplay, so I suggest you just ignore it.