Tracks added to playlists no longer showing up on linked CDJs

At home I have been using CDJ900nexus linked with rekordbox for many years with no issue. Sometimes I select the track from the CDJ, sometimes I load it from the rekordbox screen on my Mac, never a problem until now.

Now suddenly new music added to playlists in the rekordbox desktop app are not showing up when I look at the playlist from my linked CDJ. A new playlist I created this week shows up as empty on the CDJ, even though it has 14 older tracks in it. I can load those tracks onto a CDJ from the playlist in rekordbox, or directly from the CDJ from the TRACK browser, or even directly into the CDJ from an old playlist the track has been in for some time, but not from that new playlist created this week. Nor another playlist I created just now for testing.

New tracks that I have added to my collection in the past few months also cannot be accessed on the CDJ from older playlists they have been added to. The playlist is accessible on the CDJ, but the recent tracks added to it just aren't there, only when I look at the playlist in the desktop app. Or again, I can find the new tracks when i look them up by title under TRACK. I thought I was having trouble finding my new music, now I know I'm not crazy. I have been, I can no longer access any of it from the PLAYLIST browser on any linked CDJs.

Like the CDJ isn't able to access new items added to the playlist database anymore? How do I fix this?

I am using rekordbox version 6.6.1. I have stuck with this as later versions remove track tempo from playlists when viewed on the CDJ sorted by key.

Thank you, I really hope someone can help.