Hi!
I found a problem with PM6 that did/does not occur in PM5. If I select some thumbnails in the contact sheet, press F2, and then toggle a color label selection, pictures having that label disappear from the contact sheet (and never come back). In PM5 toggling the color worked as expected – pictures labeled with that color disappeared when the color was "turned off", and reappeared when it was "turned on". I hope it's a bug in PM6, not a "feature"?
All the best,
Wiesiek