Ok so i found a solution for this.
First off, this is not a collision problem. The problem is with the hair’s physics simulation not activating in the packaged build (only in standalone or PIE).
The fix is pretty simple but pretty weird tbh. just find out what’s your game’s “Default Level” in the project settings. (The first level that loads up when you open the game)
And place a character that uses groom anywhere in the world. i personally hid him below the floor. this somehow forces the packaged build to load the groom simulations upon initializing and all groom simulations will work on any level and any other character. (it doesn’t matter which character you place in the first level aslong as he is using groom with simulations turned on, all the rest of the character’s hair will work too and like i said on any different level aswell ^^)
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