In a multiplayer campaign started with 4 players, while me playing as Scarbrand and others playing the Slaanesh, Nurgle, and Tzeentch factions, whenever I fight an enemy exalted bloodthirster using Scarbrand, the game desyncs part way through the fight. This happened in two battle where I fought an exalted bloodthrister. After desyncing, we reloaded the game, tried the battle again, and it desync'd again. I auto resolved it to get around the battle.
Later, when fighting an exalted bloodthirster in a different battle, the game desync'd again. We reloaded, it desync'd again. I reloaded and withdrew from the battle to avoid it. I later reloaded the save with just myself as Scarbrand and the Slaanesh player, and the same desync happened again.
This desync does not appear to happen in custom battle mode.
tl;dr fighting an exalted bloodthirster in multiplayer campaign caused a desync 100% of the times attempted. No other fights created a desync.
-Be in multiplayer campaign (Tested with 2 and 4 players)
-Play as Scarbrand (May be optional, cannot confirm if Scarbrand is required)
-Fight a Khornite army lead by an exalted bloodthirster
-Battle the enemy exalted bloodthirster with Scarbrand and any other units
-They will fight for a while, then the game will desync. (This happened all 5 of the times we followed these steps)
I suggest using the save file(s), they were saved at the start of a fight that caused a desync on all three attempts, twice with four players and once with two players.
Details of any solutions that have already been attempted:
Attempted to reload the game, but this desync happened every time under the same circumstances