It's beyond frustrating that when you select different component states ( default, hover...) the layer stack collapses. This is just flawed in every way and it's inconceivable that it needs voting on.
it's BASIC UX and a little user testing would've revealed that it hugely increases the number of clicks to finish a task as you have to keep expanding and collapsing the layer stack for no other reason than XD decides to collapse it every time.

I'd be curious to know of a SINGLE user case where the collapsing behaviour is actually useful...

This is really annoying and slows me down in my daily work. I'm on Windows 10. Fixing this would really help! Thanks!

When working with a component, I frequently have all the layers for it open in the layers panel. When I want to change states to work on another state of the component, clicking on the state in the components panel automatically closes the component in the layers panel. This is really annoying, not to mention a hindrance to productivity to continually have to keep expanding the component layers.

I wanted to reiterate what Xavier has brought up above:
When animating between states I very often have to view/compare and edit the properties of deeply nested objects.
Each time I switch to a different state I have to drill down/expand the tree-view again - which makes comparing and editing nested properties very hard.
The expected behavior clearly seems to be that the tree-view just remains expanded and only objects and their properties change when I switch between states.

Whenever I change my component's state the left panel keeps closing the component's folder tree. Please prevent this on Windows.