I've been REing since day 1. So far I've been able to RE 23 purples from green schematics.
The higher the level of item, generally the longer it takes to RE from green to blue to purple.
I've had three lvl 48+ purples in the past two days. I don't think it is broken, just FAR more difficult to make a lvl 48+ purple vs. a lvl 10 purple.
( I did a lvl 49 off-hand and it took two weeks of RE to get from blue to purple, maybe 35 tries. It isn't supposed to be easy. )