Not to highjack this thread, but I am in same boat
latest launch box installed
mame64 .209
rom set -two folders (split) Roms in one CHD in the other,,,, both are in the same rom folder.
so I open launch box try starting game and starts up then says game over and closes, I go into Mame64.exe and how to open a game from here to see if it works? I double click on the game tittle and I get “the selected machine is missing one or more required ROM or CHD images please select a different machine,
i am am so lost with any help would be great