Official comment
I just tested in rekordbox 6.6.1 and had no problems loading Tidal tracks to four decks at a time to be analysed and ready to play in a matter of moments. Thats said, I have a 300Mbit fibre connection and I'm getting terrific speeds:

Try speedtest.net or fast.com to see what kind of speed you're getting for your network connection, as it could be rekordbox is giving up on analysing tracks because it's not getting them served up quickly enough.