Can't get Infuse to select default track

I know this is supposed to work, but just can’t get it… running 7.4.10 on tvOS 16.3.2. Have some tv episodes I’ve recorded with Channels DVR, and run through VideoRedo to cut commercials and set the default audio track to the English 5.1 audio track. Verified it’s the default track with MKVtoolnix.

But on this ATV 4k, the first track (not necessarily the default track) plays. I see on playback the “(default)” indicator, but that’s not showing selected.

The Infuse setting for audio is “Auto”. Same for the ATV4k audio language (I also tried setting that to English, no difference. Also should note that I’ve not manually set the track on the episode. Plex Web shows the English 5.1 track as the default selected.

Also tried clearing and refreshing all metadata, no help.
Is there something I’m missing?