On the new update of WoW for WotLK, MyRolePlay doesn't cooperate. Data is lost, it doesn't save, and others' MRP cannot be seen. Is there going to be an update for this Addon in the future? Is there already one? Or is there a way to get this Addon to work.

The original authors aren't in charge of it any longer.  Try Moonshyne for the newest version.  Be forewarned; it's not compatible with earlier versions (although it should be with Flag and Immersion).