I was playing h3 laso up 2 mission 4 then i accept invite from radom player he was on first mission now the game is forcing me 2 start from begining
That doesn’t sound like a glitch, that sounds like what you said, you accepted an invite from a random player who was also doing the playlist.
Yeah you reset your checkpoint save for that playlist when you accepted the invite from said person. No glitch or anything, you just physically can’t have 2 checkpoint saves for the same playlist. So yes, you will have to start over now.