I recently noticed a bug in my match history from a couple days ago where a co-op Win from the first mission Highland (Tutorial) from Arena of the Gods is counted as a Loss in my Match History. The next game was another co-op mission that Won on Watering Hole (Tutorial) that counted as a win correctly in my Match history. Gods breakdown area is also registering what Gods played incorrectly from two co-op games from Arena of the Gods I played (only played two such co-op winning both as Gaia with both being listed as Zeus with 1 being listed as a loss and 1 being a win).
I play Age of Mythology Retold using my PC from Xbox version of the game using windows 11 and you can see I got the Achievements from getting a co-op win on the same day as being registered as a loss from inside the game stats.