Battle Royal Duo & Quads - not filling lobby!

Tried for 6 times now and spent 20 minutes to get into a battle royal game. 

i am on PS5 (crossplay off) and i never get a full (80 people) lobby to start the game. 

when the lobby empties it doesn't fill up anymore and you are forced to exit the lobby and try again. Or just quit the game and ask for a refund i guess....

this goed for both duo & quad lobbies. 

can someone explain this?