The ffmpeg parameter "-movflags use_metadata_tags" leads to the following errors in the exported videos:

1. Existing tags such as comments are not displayed, but are still in the file. This can be demonstrated by copying the exported data again with "ffmpeg -i inputfile -c copy outputfile". Then they are back. Self-created tags like "MyFavorite=yes" are not displayed at all.

2. For example comments can no longer be written to the damaged file later. You can also demonstrate if you copy the exported file again with "ffmpeg -i inputfile -c copy outputfile". Then comments can be re-entered.

Workaround: Delete the ffmpeg parameter "-movflags use_metadata_tags". So the standard tags such as comments are copied and can also be edited later. However, self-created tags like "MyFavorite=yes" etc. will not be copied. But this mistake was already there before.

The error can be on ffmpeg or there must be a new syntax for copying self-created tags.