At latest release (40) I have an uncertain item (attached) but there is no confirm button or alike
Yep, this one’s intentional! The difference between “unconfirmed” and “uncertain”.
That view will only provide a “Confirm All” button for “unconfirmed” items, not “uncertain” ones. Because those are the ones that the system thinks are probably correct, and that it just wants you to confirm it to lock it in.
The “uncertain” ones are the ones that the system thinks are possibly not correct, so it wants you to go in and check it first. If those ones could be confirmed all at once, as a group, then that would risk accidentally locking in bad assignments, poisoning the models and degrading future classification results.
So yeah, “unconfirmed” means system thinks probably good, and can just fire away and confirm them all together. “Uncertain” means system thinks possibly/probably not good, and you should tap through to check it properly first.