Okay, perhaps it’s not a bug and perhaps it’s not new, but here goes:
I am a big fan of using the arrow keys to move units up and down in a(n expanded) stack.
This works great for a stack of 3 or more units, e.g., select the top unit and press DOWN to move it to the bottom, or perhaps press LEFT/RIGHT to find a place for it in the middle of the stack.
For a stack of 2 units, though, using these keys has the desired effect on stack order, but immediately collapses the stack down to its unexpanded state, which I find annoying.
Is there some setting I can switch to stop the collapse? In case this is module-specific, you could try Joel’s Barbarossa to Berlin module for an example of this behaviour.