Short version(PC version):
1) I host a coop game.
2) I set game to allow Friends, or Invite-only. I send Invites to three other friends with good/great computers.
3) We all create custom characters and then Start Game.
4) Once the last person finishes, the game screen goes full black, with no intro movie playing. Only a game-mouse-arrow.
5) We let it sit there for 5+ min and nothing happens.
6) If you hit Escape button, you can hear the menu or shuffling of a bag occur. You can actually hit the menu options like Quit game if you click the right spots.
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We started testing with me hosting a game with one person at a time. It works for everyone except one friend. He appears to be the factor.
He lives overseas, but has good Internet connection, and we can launch a Divinity Classic Edition game with him with no issues.
We got it to load one single time during our tests between myself(the host) and my friend that we had narrowed issue down to, but...
When we finished random charactor selection and Start Game, it sat on black screen for @45sec and then suddenly started playing intro movie, which I then Escaped out of, and it suddenly started to load game on both our machines.
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Extended info:
I play alot of coop with friends, and we recently had this issue playing with one friend when launching a Definitive Edition game for our first time with him.
We have no current or past issues launching the Classic Edition.
1) First, I host the game due to best connection the group.
2) We all have updated video drivers, Windows 10 patches, updated Divinity patches
3) Windows Defender Firewall is set to allow game. We have even removed Divinity from allowed apps and readded it when prompted.
4) We all play Steam version of game and we all Verified File Integrity in Steam.
5) We uninstalled Antivirus/software firewalls(except Windows Defender firewall).
6) We rebooted PCs.
7) All our PCs have SSD drives, but we still sit for 5+ minutes to give it loading time, just in case.