This sounds like the usual bug that GameLauncher has when running under windows.
It does not like having spaces in the paths. for example 'c:\Program Files\mame' does not work, but 'c:\mame' does wor.
Change your folder and path names to not have any spaces.
I don't know exactly why it works in debug mode when it does not work in normal mode, but it is a fairly well known problem with GameLauncher.