Ahh, ok. Then it was never a bl301 issue, it’s a CEC driver and/or libCEC issue.
You can enable debug logging in Kodi settings and enable the debug module libCEC.
Then restart your vim3 and try again with stable.
Then update the system with the nightly tar and try one more time.
After each try you can use this option to upload your debug files (before rebooting):
When finished you can downgrade to stable again and disable debug logging in Kodi.