When tracks/albums have matched and moved to the right pane, if they are then moved from the right pane to the left "Clusters", the original metadata on the files seems to disappear, and the "Original Value" fields change to match the "New Values" that the right pane matches of those tracks had, and the tags appear mostly identical (except for AcoustID, which is added).

This causes the clustering to be wrong, because it clusters them by the albums they were matched in the right pane as (which have not yet been written), not as they are currently (originally) tagged.

As an example, I have an compilation album where all the tracks match tracks in other non-compilation albums, and get moved to the matched right pane under those separate incomplete albums.  I then select them all and move them to clusters (in order to be able to "Add cluster as release"), but now I have just as many "Cluster" albums as all the separate album matches, rather than the one "Cluster" album that is based on the current (and original) tags.  So I can't add them as a release because they aren't one cluster like they should be.

It seems to be possible to work around this by first moving them to the "Unclustered Files" and then moving them again from the "Unclustered Files" to the "Clusters" area, when they seem to gain there original values back.  But that shouldn't be necessary and is very unexpected and weird behavior.