TL;DR:

Question banks on quizzes shared to another person vanish from the creator's library of banks, but are still accessible by quizzes that reference them.

The Situation:

I have created about 5 question banks, each containing three similar questions each so that students could be served up one of those questions randomly on a quiz or test, with the hope of reusing these for Tests and the final.

I have a coworker I work closely with who teaches the same subject. So after creating these banks and the quiz that pulled them I shared the quiz over to her.

Today as I'm attempting to build the test I can no longer see these banks, but the quiz that references the banks apparently still can, because it pulls those questions just fine.

Question:
What in the high hell is going on? How is this platform and question banking coded so utterly poorly that things simply vanish? This simply isn't acceptable and from my searches it seems like this is an issue that has been going on for years with no attempt to solve it form Canvas' end. 

I am so thoroughly gutted by this I'm questioning if I'll ever use banks again.