I don’t think the problem with this item is a hidden stat being upgraded.
The first time I upgraded a Grandfather to level 4. It gave me 101 as a blue 25% increase to all stats. Then, I came back to upgrade 4 more levels and what I did not notice is that it actually did the first 4 again and then gave me nothing. I then upgraded to 8 thinking maybe it was a UI bug and nothing. The base stats seem to be going up but the 25% I had disappeared and no new ones showed up (as there should be two). Beyond that, I also lost 4 upgrades worth of mats.
So 2 issues:
- Going back, it RE-DID the first 4 instead of going to 8 (I DID NOT reset it so I lost these mats)
- After upgrading to 4 again and then going to 8, the 4 and 8 upgrades have given me no 25% increases