What is your expectation of what should happen here? This doesn't seem like a Workboard issue, just an issue with menus in general. Should we just automatically close any open ones if you change your mind and open a different one?

Here's an example in Maniphest where menus will overlap if you open them all (up to three in this case):

Yeah closing anything else open seems to be what most other applications do.

Yeah, either closing other open menus or allowing menus to be stacked on top of each other.