Reloading a save game will break animations but switching characters in battle seems to return whichever player character you have as main return to normal. Whatever is lost on a reload is regained likely by reactivating the AI for that character which happens when you switch
Playing the through the first quests of Ch06 you'll find after being forced to switch to Noctic for the Niflheim base you'll be unable to return to your chosen character through the character switcher becasue after a battle you'll default to Noctis. You'll sill be able to save and reload and return to your chosen character but the animation will be broken as usual.
SOLUTIONS GIVEN THESE PROBLEM
fix the broken character on reload
find a way to initiate the character switcher outside of battle
change character switcher force chosen character to remain after battle
