I’m using Lakka and have made several custom playlists with 3d box art and it shows up fine for all systems except for the Nintendo 64. Like, I have all boxarts renamed to match their respective entries in the .lpl but some just wont show up. For example I have “Castlevania.png” its 480x383 and is 356 kb and shows up fine but “Chameleon Twist.png” is 480x383 and is 504kb but wont show up. All playlists are fine except for the Nintendo 64 about half the boxart isn’t showing even though they’ve been renamed correctly
I have same issue but mine it’s with MAME, I have NES and FBA working correctly but mame not working, I post more info here…
https://forums.libretro.com/t/fb-alpha-roms-unable-to-get-any-thumbnails-working/9484/5