I ran into the same thing. Made a video to show what was happening in game at the time of the glitch
So, mine wasn't a bug, it just turns out that Jinn Mesca isn't a marked one and the marked one in that area was a different npc. Doesn't help with people not getting credit for the bosses, but I was able to find this final marked one and progress.
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Made a video to show what was happening in game at the time of the glitch