Eldritch Battery question

IN PoE2 I took Eldritch battery and it says Converts ALL energy shield to Mana.
But it's only converting 215 of 750, what am I missing?

Conversion happens before increases on skill tree in PoE2.

That means that your +% energy shield nodes now have no effect and your base energy shield on your gear is now increased by % mana increases instead. Local increased ES on gear still works I think.