I think this bug is very common, after a restart of the server no player is able to connect probably. Everyone stuck at a blackscreen and the menu only shows "option", you can't abort.

Now here is the reason why this happens: (IMHO)

If a single player connects close after the restart and the server is in briefing/loading mode, the player is able to start before the first and second countdowns are done.
If this happens, the server don't load the map probably and the problem mentioned early occurs.

So i would recommend as a possibly fix and i think back in the days of 1.7 it was like this:

Don't allow any player to connect/start before the server loaded up completley.

I hope it is possible and it is not a matter of core engine modification.

If so, and you can't fix it without further access to the engine, at least you could give us the option to abort in the menu back

yup, thats very common.

but im pretty sure thats a client issue, it doesnt happen to all players.
happens to me a lot but my mates can connect without problems.

i feel like this could be related to connection problems
because it happens more to players with an unstable connection
or if the server is under heavy load (like 60 people connecting at the same time).
but that could be coincidence

right after "recieving..." right before the cloud synchro you kinda time out into blackscreen

at the moment the "wait for the server to complete starting procedure" tactic doesnt work
because the server needs at least one client to start properly.
a completely empty server will not start.
it will be stuck in "creating" or "waiting" until a player connects.

there will be a reason why they disabled the "abort" button,
but i really want it back.
you could just hit abort, go back to the lobby and try again.
now you have to restart the game completely and thats annoying.