Shift+Tab not opening steam in this game only, can't invite or join friends.

The game is Crab Champions, not sure if this is a good place to post this but the game's subreddit is pretty small and i'm not finding much help on google.

shift+tab doesn't open steam so i can't invite, and joining invites does nothing. there's an in-game multiplayer invite function but it doesn't work for me either.

i get the "do you want to allow this app from an unknown publisher to make changes on your PC" message each time i open the game, and my in-game name shows as my PC name and a bunch of numbers rather than my steam name. not sure if any of that is related.

appreciate any help.