The line displayed on the device does not work .
For example: 20% chance to recover 165 Mp when attacking
It does not recover all the time when fighting monsters
"HP Recovery Items and Skills +x% potential does not work " is a known bug. I believe this potential line is the same and is too irrelevant to code in.
Invest in a pet with auto pot skill, and many Power Elixirs from Miu Miu.