On two of my characters, seasonal, in Torment I/II or III, whenever I zone, the active quest is dropped. Can be teleporting, crossing a zone boundary, entering/exiting a dungeon…
On my lowest character it doesn’t happen and that one is in Hard at the moment.
Edit:
The lowest character is now also affected. I started noticing it with the quest “The Priestess Horadrim”. Expert tier, level 46.
Edit 2: 100% sure the trigger is receving the quest “The Priestess Horadrim”. Paid attention to it levelling another character and after placing the two relics and the quest switching to that one, the next zone active quest was gone.