Hi,
It does not matter which of us joins last. The combination of those four players will not work, no matter who hosts and in what order we join the match. They player who switches accounts can join in any order and it will work because there seems to be no conflict with his alternate account. To be clear, the problem is not with just the four of us. We are in a PSN chat group with roughly 60 people and it happens to all of us, depending on what combination of players are trying to play together. Some of us, like myself, seem to have more issues than others but it happens to everyone.
Also, while I am most interested in private matches so that we can all play together, the problem is not confined to private matches. It happens with ranked matches as well.
This is a video of it happening in a ranked foursome match. This occurred at 1:09 PM EST today, 2/2/2024. I have played several hundred matches with my teammate in this video, and now we can very rarely play together.
This is a video of it happening in ranked stroke play. You can see that my first attempt appeared to work, but my 2nd and 3rd attempts I was kicked, presumably because there were "incompatible" players in the lobby. Obviously I don't know who else was in the 2nd and 3rd lobbies, but rest assured they were all kicked as well. This occurred at 12:34 PM EST today, 2/2/2024