Jumps to 400k ?
It's similar to a previous bug I already fixed about the share counter (which was a cosmetical but misleading bug). And again, only for CN-Heavy. I'll take a look back once i'm done with the Watchdog.

RX550 : my lovely cards, my underestimated favorite. With JCE (and in a lesser extent Stak or others) you can easily pull ~500 h/s from them on v7. Thanks to their memory controller which is the same as the bigger rx560, and for which JCE has dedicated code. So you get a quarter of a vega for a fraction of the price, best efficiency.

The vega jump happened with Cast and the BetaBlockchain. Now the recent 18.x drivers give full power of Vega and we're reaching hardware max at ~2100h/s. It still requires dedicated code to have good performance but no longer hacks to force Compute mode.