Looks like the server is running a different mod, which probably treats the entities in the map differently. I don't think this is a bug with Paintball2, but whatever jump mod the server is running.
I'm playing on "Crack' the Jump" server, i don't think there is any mod for that server. I will ask the Administrator to be sure.And my HUD is a mod like PDCP created by Richard. That we can see on one of his screenshot HERE.