fender357 Hmm strange. I'm not sure if there's a list of supported ROM file types, but we are using the latest version of RetroArch for all consoles, so you can look up info about that. For arcade games, we use MAME 0.178 at the moment, but sounds like you're issues are limited to consoles.
Also, we've discovered a bug that causes ROMs to not show up in some cases, despite being in the correct directories. It seems to be mostly affecting N64, but it's possible it's affecting other games. We should have a fix for it very soon, but it's possible your issue is related to this.