The debugger control buttons have an unclickable zone about halfway vertically.

The bottom and top halves are clickable (and the hover state is properly set), but a few pixels wide in the middle there is an inactive zone.

The bottom of the buttons is also overshadowed by the resize area of the pane below, making the actual clickable region for these buttons quite small.

Unfortunately I cannot seem to screenshot this behaviour with mouse pointer nor record that part of the screen showing the weird behaviour. In essence you should see it by moving the mouse cursor from the bottom to the top of any of the debug control buttons shown in the screenshot