"Local" EH set server side on a vehicle does not fire on dedicated server when there are 2 players on the server. If one player leaves, EH fires all at once. So for example if it had to fire 3 times and fired none, when 1 player leaves EH fires immediately 3 times.
Instances set on clients fire without problem
Add "local" even handler to a vehicle on the dedicated server at every locality, player1, player2 and server.
Get in vehicle driver seat
EH fires on both clients but not server.
enter vehicle driver seat with another player
Same situation, fires on clients not on server
Quit server with one player
EH immediately fires on server 2 times.