I too see this bug, I narrowed it down to one of the first four and last two of the factions as you step left to right, top to bottom through the factions.
So 1 of banner lords, high elves, sacred order, or barbarians.... and one of knight revenant or dwarves.
Myself here having same issue , I just made a thread and start read the forum to see any one else having same bug.
I also wrote down and make a check list . I ascend multi time on those faction that haven't mark and mine still say 8\13 . For example orge tribe I ascend 3 time on 2 star on 3 star champ and still not count . I need some potion back .
Also for future update I suggest add a future where the game let me know which faction already ascend and which not.
I am also having this problem. I remember, however, that the wording was incorrect for another mission. I wonder if we need to do something other than ascend a champion to get credit?
I've tried ranking one up, but that doesn't count.
I also ascended one three times, to unlock their skill, but that doesn't work.
Hopefully we'll get an anser soon(TM). Sadly, the Forum isn't managed quite as well as you'd like. Answers take some time (and mostely consist out of "we'll tell the programmers") and cleaning the spam is done sparesly (especially before 4pm European Time ).
I know there aren't a lot of mods and they have quite a lot to do so I don't blame them, but I'm afraid until we get some News on this it might take a while….
just like we'll never see any compensation for most of us having issues with the game the last 2-3 weeks (as mod's put it "we don't see it so it must be on your end" or so) but get small comp's for the updates it's a game of Patience for all of us ;)