I still have an occasional crash when saving a file rendered with the x265 codec, but a more frequent problem is that the last few seconds of the output file (MP4) is truncated. If I take the same file rendered with x264, all is well.
I start with a huge (15GB+) .TS source, then render it to an MP4 file of manageable size (5-7GB). If the renderer uses x265, that's when the problems arise. The same process with x264 render is trouble-free. I have about 5 files rendered with x265 that will have to be re-rendered.
Any suggestions, other than work with the x264 versions exclusively? I can use either one.