Make In Progress and Fresh Start Commence windows look exactly the same. Even in a pre-form you only see your single roll ready to Commence. That way you have no idea and can't fish for in progress. If you still want to leave a fresh start eat the penalty and leave, at least everyone else is in and doesn't have to wait.

At the same time make it so we can invite people from inside a dungeon. That removes the "fishing for my friend's run to help" excuse. I've done that and it is annoying I have to gamble RNG if I am able to help my friends.

Then, only dish out loot after the final boss. Each boss you roll, doesn't get dropped until final boss. That also removes the "loot and scoot" crowd.