Emby Docker Container issue - possibly after 6.9.1 upgrade ?

Firstly, the Emby Beta was updated around the same day as the Unraid server, so this may be emby's issue, but may also be something I have to configure on unraid for the 6.9.1 upgrade (I was on 6.8.3 beforehand).

The issue - the emby conversion process is burning in closed captions - it did not used to do that.

I have a cheap NVidia GPU card in my server as it is AMD with no onboard graphics and needed something to boot with.  I dont pass it in to VM's or anything.  I notice some stuff in the 6.9.x about making mods for built in graphics drivers - not sure if this relates to the issue.

The emby server reports this in the hardware detection log at startup - I dont remember this being there before, as I have 8 CPU's and was software encoding.  Emby is set to NO for 'Enable hardware transcoding' :

    "Devices": [
        {
            "DeviceIndex": 0,
            "DeviceInfo": {
                "VendorName": "NVIDIA Corporation",
                "DeviceName": "GK208B [GeForce GT 710]",
                "SubsytemVendorName": "ZOTAC International (MCO) Ltd.",
                "VendorId": 4318,
                "DeviceId": 4747,
                "SubsytemVendorId": 6618,
                "SubsytemDeviceId": 21344,
                "DevPath": "/sys/bus/pci/devices/0000:05:00.0",
                "IsEnabled": 0,
                "IsBootVga": 1,
                "Error": {
                    "Number": -1,
                    "Message": "Failed to open the drm device (null)"