Suggest as part of the next test, a test with and then without rcd files. (virtual rides).
Can test with, then leave the server clear our rcd files, (server too) and go again.
They have been a real issue on some servers.
I also suggest when we try with rcd file to give the time to download all livery, restart the server (if it doesn't mean that all livery have to be downloaded again) and try a race and we should stay all together to see if cars disappear. On this race i think server should be close so we are sure that aren't people enter in the server to create this issue