I can’t load the saved game. Auto-translated

The issue is as follows: We're playing with my brother over a local network, each on our own computer. I was unexpectedly disconnected from the game (I was the host), and there were no autosaves. My brother saved the game from his computer, but I can't load that save. The game recognizes the save file, and I can load it, but when my brother joins the created game, the "start game" button is inactive, even though both of us have set our status to "ready to play." The same thing happens if he hosts... the "start game" button is still inactive. Please advise on how to fix this and why it's happening. Thank you in advance.