MAME internal menu - unable to select any option

[bollwerk]

Pi Model or other hardware: 3
Power Supply used: CanaKit 2.5A
RetroPie Version Used: 4.2 IIRC
Built From: Pre made SD Image on RetroPie website
USB Devices connected: Xbox 360 wired controller, usb mouse and usb keyboard
Controller used: Xbox 360 wired controller
Error messages received: None
Log found in /dev/shm/runcommand.log (if relevant): Not relevant
Guide used: RetroPie docs site
File: not relevant
Emulator: lr-mame2010
Attachment of config files: Not sure which config file to check
How to replicate the problem:
The issue I'm having is with the MAME internal menu when inside any emulated arcade game (using lr-mame2010 at the moment). I can bring up the menu with the trigger L2(?) and I can navigate up/down, but no button on the controller will select/open any option. However, all buttons work as expected when actually playing a game. I do not have this issue with lr-mame2003. Did I break something somewhere? Or do I need to edit the default config for lr-mame2010?

Thanks.

[dankcushions]

@bollwerk mame2010 isn't really recommended, but you could look at the mame2003 docs to show how you would revert to default controls: https://retropie.org.uk/docs/lr-mame2003/#mame-menu

if you hunt around your rom and BIOS directories, you may find the same default.cfg for mame2010. i'm not sure where it will be. if that deleting that doesn't fix the issue, then maybe mame2010 doesn't have good default controls here - a keyboard might work?