The occasional embedded SCC (CEA-608) subtitle isn't displayed

I have an mp4 file with embedded SCC closed captions. Most of these display fine, but the occasional caption doesn't display.

I have included an example below.

If I use ccConvert then I can see the subtitle, and when I burn the subtitles in using Amazon Mediaconvert then it's there, but VLC doesn't display it.

You can see the file with embedded subtitles here:

https://www.dropbox.com/s/4ix4cypxky7xikg/test_3_subtitled_with_embedded_scc.mp4?dl=0

And with them burned in here:

https://www.dropbox.com/s/4yp9f5vz378vn1k/test_3_burnt.mp4?dl=0

The missing subtitle is at 06:19

Any help would be much appreciated!