It's good to know I'm not the only one at least. I've unlocked several level 50 purples over the past month. Working on this latest one though and it's been insane. It's been well over 100 REs now (keeping count by how many vendor mats I've bought, not counting the mats I get back from the RE themselves) and I still haven't been able to unlock the blue schematic. This seemed way out of whack as, like I said, I've unlocked several level 50 purples over the past month.
So, I petitioned to see if it was a bug and if the blue and purple versions were actually in game. The CSR did confirm that they are in game, just that I've had terrible luck.
I'll keep at it, but yeah.. something has definitely, without a doubt, changed.