iTunes "grouping" field to RBX "label" - refresh?

^^ That's correct, the reload button doesn't work, also what's more, the first time you use the reload button on mp3 files (and any time you use it on AAC files) it overwrites the imported Grouping data with the information stored in the Label ID3 tag, reentering that data in mp3's seems to make it permanent though.

How many tracks are you editing?  The way I did it was, once I'd finished labelling or grouping everything, I created a bunch of smart playlists for each label/group in iTunes, Imported each of those smart playlists into RekordBox (if the music's already in your RB library, it'll just add it to the new playlist) and then edit each label in one big sweep.

Hmm right. I'm currently using it for about 1100 tracks. I had already created a workaround using iTunes smart playlists, which is probably what I'll need to stick with, because I had the "bright" idea of putting multiple tags/keywords in the grouping fields, comma separated. So your approach wouldn't work for me because of all the possible combinations of my dozen-or-so tags.

Cheers!

Ah got ya, I'm not sure if this is helpful or anything you want to mess with at all, but www.dougscripts.com has a wealth of scripts which are invaluable for iTunes library management, there may be very well be one in there that transfers Grouping into Comments, and then it's a matter of just updating your Smart Playlists to search comments instead of Grouping, freeing up that field (again, not sure if that's helpful or not, just trying to come up with possible work arounds :) )

Looks like an awesome resource, I'll check it out. Thanks!

Umm.. why no show "grouping" option in the first place?

Sad that the grouping tag is not supported - finally no use of rekordbox. Label is also filled. I have over 40.000 tracks in my collection.