It looks like the problem has been fixed, as described on the GitHub commit as the previous buggy code attempting to open multiple modal dialogs and hanging the Editor when updating asset references:
https://github.com/EpicGames/UnrealEngine/commit/658a3ceb7d3e79f2c7678e8c158b78683d2b0cef
Hopefully, that was it, and the accumulating orphaned references from the older Sequencer files is not significant. I also see that specific bug report has been reopened after relaying my notes about the hex editor view.
Thank you again for truly resolving this problem. It is very refreshing to work with someone who gets things done!