Cant enable brush stamp preview?

I used to have it enabled and it was soo helpful but it just turned off for some reason? For the life of me I cannot figure out why I cant enable it again??? I'm just using the default brushes and triple checked that the one I was using was a stamp brush.

Tried uninstalling-reinstalling, reseting the ipad, reseting all preferences.

Do I have to have something else enabled to bring it back?