OpenCL bug 0.2-10: i could reproduce it on my rig by using exotic characters in the path where JCE exe was, and this case is fixed. But there may be another cause of bug. Did you use non-english path too?

Hashrate: first, yes, the +15% is not fake, but it can be canceled by the higher instability on some cards. On old cards, it's +20% faster and stable, easy. HD6000, HD7000, R7, R9... On big RX and Vega, things are more complicated.
I read here opposite results, so:
* Ensure you're talking about CN-Heavy and related, CN-v8 is not concerned by the 0.33b6 release
* Is it unstable on the 8Gb RX and Vega only? Sure that's the most common cards, but if this is the status, it's an important detail to track the bug down. I did my long-run tests on 2G and 4G cards only so far. If I need a 8G card to reproduce the bug, i've some, so i need to focus on them.

I suspend GPU support and dev for now, going back to CPU version where i've a fistful of Github tickets to close.