Since I had no luck asking in the quick questions-thread and I haven't been able to figure this out, I'm asking here...

I have a problem with a quest stage: the objectives should be updated when the player grabs a quest item, the alias has a script to set stage on acquire. However, one of the 3 testers I've had says that the quest objectives don't update. Aliases are filled, the quest marker disappears and the stage is set correctly, but the objective doesn't update. I cannot repeat the problem myself nor did the 2 other testers encounter it. I've generated the .seq file and the tester says he's using a clean save. What could be causing this?