Stage area empty when merging

When merging branch B into branch A, and if there is a conflict or more, the stage area is empty, but the right pane shows a file selected.

If I nervously tick the checkbox next to the "staged files", or "unstated files", the window refreshes, but the merge flow is broken, forcing me to do a hard reset.

I can solve this by changing the view options, for example switch between "show only conflicts" and "show only pending"