Donator reserve slot broken?

Whenever the server fills up and I decide to leave for a bit and come back later or retry in console to switch classes, it will either say "The server is full" or "Disconnect: Connection rejected by game" upon a rejoin. I should have a reserved slot for each Saxton Hell server, so the question is; why is this happening?

MvM is a little iffy with reserve slots because of the mvm bots that take up player slots. You have to sort of time it right between waves when bots aren't spawning.