Hello Ozzi,
    Thanks for the reply. I installed BugSack and BugGrabber with DugiGuides as the only other mod. The Sack stays green as I replicate the disappearing quest list issue mounting/dismounting Dragonmounts (not using a macro as you say).

    When I ran /dugi fix I did get a “fatality” message and red Sack. The text of that is attached.  I hope that is helpful.

    I re-installed DugiGuides from CurseForge, no change to symptom.

    Thanks again for any guidance!