Thanks for the reply! When Moneydance loses keyboard connectivity, the mouse still works and the UI is accessible via the mouse, so it sounds like perhaps not an issue with a locked UI due to a long-processing or deadlock thread.
I did find another user having this issue with Moneydance, and someone (not sure if they’re a user or with Moneydance) seems to think the problem is specific to Mondeydance.