Ok I did some tests:
1) I first had to correct the SAV files, because both of them had the Entente as "human" player
2) Then I played your save(s), without no loss of battle synchro... I founght the whole August 1914. No problem.
3) So I started everything from zero, new game. I fought the whole pre-turn + turn...
The only one problem has been a loss of synchro due to a Reaction. So I suggest you to avoid the Reactions...
Otherwise it's a connection problem that causes the loss of battle synchro.
I will investigate again later.