RDE doesn't appear to be functioning correctly on my game. BCSO addon isn't working either and in blaine county/outside the city, the only responding cars are one man Sheriff SWAT units in patrol cars. Highway patrol doesn't patrol either and whats more, if I try and spawn the highway cars they just don't spawn, no invalid model message or anything. City cops don't seem to be functioning correctly either. It doesn't crash either which makes me think its a scripting conflict or something but I have no other wanted/dispatch scripts running.

I have no idea whats causing this as usually I can solve my own problems but this one has stumped me as all the correct files are where they should be and the only thing that could be causing this error is either my modded cars (unlikely I think) or LSPDFR itself, which I doubt. 

Help would be appreciated many thanks.

I would suggest reinstalling it completely , if you are talking about "backup units" in LSPDFR , i would say that you're gonna have to tweak the "backup.xml" file in your LSPDFR folder , if it's about patrolling units and models not spawning , like i said before , reinstall RDE.

Hope that fixes your issues.