DVB-TTML ( ETSI EN 303 560 ) reference streams fail to detect any selectable subtitles

When loading the DVB-TTML reference streams, available at https://dvb.org/specifications/verification-validation/dvb-ttml-subtitling-test-streams/ VLC fails to enable any subtitle options, nor select any subtitle language or track.

Those streams are correctly identified on DVBInspector.

Last tested on VLC 3.0.21 Arm64 MacOS.

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