I've been having this issue for months, and now that the Xbox Companion App has been crippled, I can no longer join game sessions from friends unless they invite me. When they invite me, I get an invite via xbox game bar, and the xbox console companion app. If I accept the game bar invitation, it tries to launch steam (I have already gone through the hassle of unlinking my steam and xbl, to no avail). If I wait for the console companion invite to come through, I can finally join.
My fear, is that the xbox console companion is set to expire. The new app, Xbox App, doesn't give me the option to invite or join on a friend. It exists (unlike the console companion app), but is grayed out always.
Long story short, I have owned SoT on Windows since January 2019. I bought SoT on Steam approximately 6+ months ago, and ever since I linked it to my xbl, I have never been able to join a friends lobby.
This is incredibly frustrating, and is an issue Rare and Microsoft need to address, because it's inevitably going to drive people away from the game.
I do not want to play my steam version of the game, as it is way more buggy when it comes to alt+tabbing in and out of the game.
If anyone has a fix for this yet, please, I am all ears.
Edit, I have tried uninstalling the Steam SoT version, but it just prompts me to install the game when I try to join a friend, instead of launching the MS Store variant. Very frustrating.