Soft Resetting not working for Hidden Grottos

Does anyone have any idea why soft resetting doesn’t reset hidden grottos? Im trying to get a delta munchlax but everytime i soft reset its always a max potion.

it works but you have to be outside of the grotto never having entered it

Yes I saved before entering but still not resetting

idk then

It resets, but it takes a good amount of tries. I sat at one for a Beldum for like 20 minutes.