The vehicle desynch/floating/invisibleness may be due to the latest arma 3 update, but you can't deny the fact that the server cannot handle 100 slots of Altis Life as the mission has so much going on.
It cripples in the last hour. Even tonight, there was an extra restart at 11pm due to the vehicle unlock glitchstopping anyone driving anywhere.
Also, when the server is under strain like it is in the final hour running at 100 slots, is when the saving of gear/cash is most likely to mess up. For example tonight before the unscheduled 11pm restart, I had been on a few hours and changed my gear throughout the session. Synched data regularly. Then died in a hostage situation and spent the last 20 minutes running around Athira chatting to people in my civilian clothes.
After restart, I log back on and I am fully geared as if the 2+ hours of gameplay never happened. My items/cash had reverted to the same stuff I had in the morning..... Not that I'm complaining as it saved me a trip to an outpost but if I had spent all that time doing nosetalc runs to build up cash, I'd be miffed.
This is the problem I used to get with 100 player server, as well as the desynch.