There has been no mention about fixing this issue (which is not surprising as PC got the major shaft in gears 4, especially with the nvidia issue that made it nearly unplayable for many people for a year plus). I see so many people with the same issue on steam. You redeem a code on the microsoft store and it does not show up in game.
I’m now up to 5 different codes redeemed without any in game content. This is frustrating especially when most purchases are merch related to supporting gears. I have seen that most ticket responses just show concern to the UE preorder bonuses.
The only known fix currently is to DL the game via the microsoft store with the game pass and log into that version. That then redeems the skins and once they show up in that version, they will show up in steam. That however is a ridiculous amount of work and should not even be considered a “fix” especially since you have to pay (albeit a dollar, buts its a matter of principle) the game pass.