So a bug on my Nintendo switch is that every new calendar day (in game) my Hero class resets to Warlord, and I get the troop i leveled mostly as Warlord. Played ~5 hours yesterday as Bard and with a different troop but it was back to Warlord this morning.
This also happened yesterday when the new Daily login/calendar popped up.
Edit 7/4 : This bug happens in Pet Rescue too. It remembers the class, but the troop goes back to the ones i used during my first Pet Rescue every time…
Edit 8/4 : I think its related to the Pet Rescue mostly. I kept my class at yesterdays calendar switch, but the Pet Rescue triggers the class & troop change every time.