Sharing a Question Bank with an External Connection?

My team works with several other teams -- both ones that are outside of my organization, and ones that are inside but using separate Articulate 360 accounts.

I have no issues sharing our Rise courses with these other accounts -- as you can see in the attached screenshot, we have "external connections" that allow us to do this seamlessly.

In our training plan for next year, we are looking to use Question Banks for the first time.

I've created some test question banks, but I don't seem to be able to share them with our external connections the way that I share my courses.

Is there something that I'm missing here? Or is there some reason why question banks are not shareable?