From: Bratislava, Slovakia
Well, it is not a mod related, but a game version (exe) file version difference between you and your opponent. IF these are different then a SYNC bug is (very) likely to occur. First try to get both of your game versions in line (game install + patches), then you can add mods, map-mods, graphics and stacking limits updates (both should use the same, but actually I think map mods could be differing if using the same pwhex.dat - because they change the visual things only, also the mod with unit-emblems, etc.).
What you definitely need to have in line:
- game version (same patch)
- Standard/extended map (pwhex.dat)
- Stacking limits (pwhex.dat)