OK, and now that you removed standalone mame did you change the games to use Retroarch?
In your first posted pics when you showed and edit screen for Knights of the Round you have that game using Mame. Did you change the games to Retroarch? Even though you have it set as default in the emulator settings you still need to change the emulator for the game since you had it set to Mame.
Right click a game and go to the emulation tab and make sure it is set to Retroarch then launch that same game and test if it works.