I wonder if its a bug or a settings issue, I haven’t been using Island Settings for players for a long time, so I haven’t encountered this.
In Island Settings do you have a Default Class set or Revert to Default Class at End or Round enabled ?, this sometimes does funny stuff if set but not setup elsewhere.
Do you have a Class Selector, Designer or Teams Setting Device in your Project ?
If you were to use a Class Designer Device for your player settings and set it as the Default Class in Island Settings, it’s the highest priority way to setup players and should stick the whole game.