I installed two things, a pack and a separate car from a different author. Both work, however, the vehicle extras are broken. When I go through my trainer (tried multiple), toggling extras does nothing. If I repair the vehicle, the extras show up. I tried to force the extras to spawn both from the vehicles meta and from ultimatebackup backup units, neither worked. Additionally, I installed two of the cars from that pack into my sheriff and sheriff2 slot, same exact thing, extras don't work. I'm really confused, because to my knowledge, fivem cars are built the exact same way as non els for singleplayer. There's no reason at all the extras, of all things, shouldn't be working.
This probably isn't exclusively an LML issue, but since LML is aimed at letting you install these fivem cars for singleplayer, I thought it was worth mentioning.