This is odd indeed. Also mentioned here: Things that need some improvments! (point 2)
Two possible solutions:
- In the moment the user hides the active collection, the scene/master collection could be made active.
- If the user adds an object to a hidden collection, it could automatically unhide to reveal the newly added object.
I’m not sure though if that would break someone else’s workflow.
What determines the active collection in general seems flawed to me. The only way to make a collection active that I know of is via the Outliner, by clicking on on a collection. Clicking on a child object does not change the active collection, which is counter-intuitive in my opinion. Does this actually serve a purpose?