Banging my head trying to sort this out so thought i would finally ask for help! This issue is with Launchbox 1.0 for Android.
I have imported the full 0.139 mame set and configured to use Retroarch with mame2010 core.
However, some games just hang with launchbox saying "loading" at the bottom. It does appear to load Retroarch (sideloaded 64-bit) and if I wait long enough my tablet will tell me that the Retroarch app is not responding. If I independently load Retroarch (sideloaded 64-bit), go to load content and choose the ROM from the full mame set folder, followed by appropriate core (mame2010) then the game works just fine.
This is where it gets weird though: as an example I will choose A.B. Cop using the abcop.zip mame 0.139 ROM. This is one of those games that hang when I try to load through launchbox so I did a little experiment. I deleted the game from the list and proceeded to copy the abcop.zip ROM to a separate folder simply called "test" with no other files in there. In launchbox I went to import games, arcade, and chose the folder I made called "test". It found the abcop rom and succeeded in adding it to my arcade list. Now if I attempt to load the A.B. Cop game it works! Why does moving it to a separate folder cause it to work from launchbox, whereas when in the full romset folder it doesn't? It's the exact same rom file. There are no additional versions.
A lot of games appear to load and work fine after i've imported the full romset but there are a significant number that have this behaviour described above, where when I move the ROM out of the folder and then re-add it, it works fine.
Please help!