Can't Get More Than 4 People To Join

Like the title says, we can't get a 5th or 6th person to join (host is using Party Limit Begone) without them getting a message saying, "the party is full, no companions can be dismissed". I've looked online and all I can find are hits from 2 years ago and none of them seem to offer anything that helps us in our current situation.

Anyone have this issue and/or know how to resolve it?