A quick update, I found a version of x264, that seemes to be optimal for encoding with Ryzen 8 core cpu's, where I am hitting 40 to 60fps, slowest setting, on the second pass, depending on the encoding bitrate and it almost maxes out all 8 cores in both first and second pass... and most important no crashes....
If any one am having the same problems with Ryzen and bd-rb crashing I would be glad to help and share the x264 version I am using