Players get kicked from Whitelist even though they are still invited

My friends are invited. They have accepted the invite and have been playing without issues.

After a few days some of them message me that they suddenly aren't on the whitelist anymore. See Screenshot_2.png.

This happens even though they are still in the invited player list. See "screenshot 3.png" the players' names are censored for their privacy, but I marked all the affected players with an arrow to show that they are still invited, and therefore should be on the whitelist.

 

To temporarily fix this issue I have to remove them from the invited list and re-add them. Since I am not available 24/7 to do this, it has been causing my players to miss out on some game sessions. It would be great if they weren't kicked in the first place.