May be this helps:
https://wolcengame.com/forum/bugs-issues/technical-connection-issues/fix-blackscreen-in-loading-screen-after-starting-an-online-game/

But we still need a fix for this...

Same issue here, but, I play with a friend who doesn't seem to have this precise issue. He has others though, like seeing me offline when I'm online, or getting disconnected.

We spent a few hours in 2 days, trying to fix that by every means possible.
But I think it's just the game that needs a fix and I doubt we can do something about it :/

Edit : I tried that VPN fix they talk about in the link above, and it WORKS!!!!!

sadly don't work for me - but I'm in the same boat... black screen for all of my online characters... since DAYS... what lazy devs... srsly - never seen this anywhere before...

Same here. Can't do anything online suddenly. Worked fine for a week then suddenly gives black screen when loading into a game.

Same here!!

Same here, NA West Coast server

I got a solution that worked for me, posted originally from Frebys on this thread: https://wolcengame.com/forum/bugs-issues/technical-connection-issues/black-screen-of-death-2/#black-screen-of-death-2-ZaB0 ...(about the 10th reply down).

He says it's a US server issue. Log onto an EU server and the game should load. Worked for me, albeit with higher ping than I'm used to.

Still a good fix for now until the devs sort this out. Hope it works for all of you!