I've been playing since release and something about the enchancement system seems to be wrong. 

1. When I'm trying to collect Failstacks most of the time the first 5 tries it is a success between 2% and 5%. No Failstacks.

2. On the other hand if I try to go to Duo I need 40%+ and maybe have some luck. On one item I wanted to go to 15 and it needed 83 Failstacks. My Awakening weapon to Duo were 65 Failstacks. Meanwhile my Failstack item has one successs after another. 

All of this since release.

So is this the intended system or is this a bug in the formula. I've red on reddit that there was a bug like this on PC.