Sorry to bother you again but when you save the game, press f5 to return to the title screen and press continue, your stats are reset, is that intentional or a bug?
When i close the game and open it again the stats reset too
Remember that in RPG MAKER MZ, F5 does not send you to the Title screen, it reloads the game.
And your project must be bugged, or you will have a compatibility problem. I have tested it in a clean project and installed the Visustella Core and I have had no problems. The character stats are maintained when the equipment has evolved.
I recommend that you try to test it in a new clean project to see if it continues to happen to you.