Huh... I only used the MZ Demo, where only Neel_SoulsStatueBar is used, so i don't know, maybe it's a bug of the plugin itself or the fact that i'm on the 1.7.0 version of MZ. Maybe it's the current version of the CoreScript used?
MZ Demo Project seems to be working for both saving the game after winning a battle and saving the game after escaping a battle. This is for RPG Maker MZ v1.8.0. Perhaps updating your version of MZ will help resolve these issues?