Firstly, no issues with h265 with the official rasp pi 4 build.
I have been using the retroarch version from here. Release 2019-08-23-RPi4 · magicseb/LibreELEC.tv · GitHub
Everything runs better than expected, but the only issue is h265 files that run on the other build don't run on this one.
Log files: http://ix.io/1uio
Crash log also