so the thing to note here is lr-mame is in the 'experimental' section of the retropie package manager. experiments fail :P
It wouldn't be an experiment if we knew what was going to happen :)
lr-mame2003-plus seems very reliable for me, with helpful features over lr-mame2003. Is there a list of remaining issues, or a process for that to go through before it becomes a regular optional or main package?