Audacity versions 3.2.1 and 3.1.x are losing most metadata when Audacity re-saves an export file.
Only the basic metadata is retained, and the rest is lost including AlbumArtist!
The forum reports “observation is that at least non-standard metadata is being discarded, is absent, is lost by Audacity, when opening and working with files in which this metadata is pre-existing. For instance, “ReplayGain” metadata existing within files.”
This is naughty of Audacity as this issue was identified prior to these releases but not dealt with.
According to the forum version 3.0.5 is the last version before this issue manifested.
See [3.1.X Metadata absence/loss - Audacity Forum](https://forum.audacityteam dot org/viewtopic.php?f=46&t=121636)
I will re-install that version. Now all OK again back with 3.0.5.