I am having the same issue as OP.
Not only that, but the neogeo system section added literally all copies of my arcade roms even though I specifically selected the 130ish games from my neo geo folder when scanning. Can't seem to clear the neogeo list in launchbox after the fact either.
Also, weirdly enough, some of my games say within the genesis system for example would not run within launchbox, but would run perfectly fine while using retroarch plus natively...
Nvidia Shield pro 2019
-mounted internal storage which includes the retroarch app of course.
-roms on external storage, as well the launchbox folder (defaulted to external during install)
Update:
Was able to get everything working in regard to TurbographixCD and Intellivision by turning off "System files are in content directory" in the "saving" options within Retroarch plus (must have advanced options on). I forgot I changed that a while ago when trying a different front end.
But still, same as OP, I am having issues with Arcade and Neogeo within Launchbox even while using cores that work just fine within Retroarch itself.
Common errors for arcade seem to be "unable to load all rom files", while Neogeo seems to just blackout until returning me to the Launchbox game selection screen.
The cores that work within Retroarch are Mame_current and FBNeogeo. But again, once I try to open up Mame or Neogeo games from within Launchbox, it doesn't work. So odd, most everything else works just fine so far.
