AMD RX 6800 XT's throwing invalid shares

[jharvey6]

I just setup this mixed RIG and it was running fine for 3 days. Then without any modifications it started throwing invalid shares error and the performance fell way off.

I haven’t done any OC on them as yet. I usually let things lay awhile before monkeying with performance. Any ideas why this is happening. I’ve tried what I thought was everything.

[jharvey6]

So I tried the PhoenixMiner driver; no joy. So I went to NBMiner and the Invalid Shares subsided but now the AMD cards are stuck at ~54MH down from about 72. OC settings have zero impact.