@Draco9990 - I wanted to get the full info on this out to you but the character limit in the Comments is 1000. I was in the game with Kyoojin, I'll describe what our experience was.

We set up a four player game, two on the Deck, two on desktop. We would all move into the same location for a battle. It would usually start without issue, all players finish their turn, the enemy would then take their turn. The change in sync usually happened on round 3 or later, and it was intermittent. No real definite pattern to how/when it happened.

When it de-synced, that player would finish their turn and not see any updates until after the other players saw the enemy start and end their turn and then complete their entire next turn.

To tell it as a story example, Players 1-4 would all take a full turn, complete their turns. Players 1-3 would then see the enemy counter attack and finish the enemy's turn, then the players would take their next turn and finish their turn. ONLY THEN would Player 4 see the enemy's counter attack (or whatever moves they had chosen) and be able to take their own turn. The moment they completed their turn the enemy would continue with the next attack for Players 1-3. Player 4 would usually not see this as it happened, would have to wait again, until the end of the full battle.

It happened randomly, sometimes one player would be out of sync, sometimes two, and usually it would be independent. This means it was essentially as though each player were taking separate turns. The one thing that stayed real-time for everyone was the damage done to enemies or players. Whenever the enemies would be attacked, whoever was out of sync would not see the attack happen but WOULD see the drop in HP.

Only a few times (we believe it was during a boss fight or elite fight) did we see it get so far out of sync that the HP numbers didn't update accurately when damage was given/taken.

We're not sure if the Decks are part of this issue or not, but we'd love to be able to have it resolved to play as it was meant to be played.

(Also, little side note - the Slime boss split HP was better after your fix, but two things: it didn't seem to affect the new HP after their split no matter how much we had damaged them pre-split, and the new HP for the split versions of the boss were sometimes different for each player in the team.)