Hair slipping but grain not ready?

I soaked a recent hide in hydrated lime solution for 4 days after fleshing. Hair was slipping very easily but I couldn’t get the grain to start peeling. Do you all have any advice? From what I’ve seen hair slippage is the sign that the grain is ready to go but apparently not with this one. It was a 4yo whitetail buck, I’m using HiYield horticultural hydrated lime and it was stored in a shop while soaking, the temps in the shop ranged from 40deg to 70deg throughout those days. I also stirred the solution a couple times a day.