Rekordbox 6.5.3 Waveform Preview missing after XML import

Can anyone get me out of this mess -

I was doing some updates to my library via Rekordbox Cue and Key Tool App  - converting all my hot cues to Memory cues.

After updating my tracks from the new imported XML  I now have many tracks that have lost their waveform previews (I've attached a screenshot). Hotcues (and new memory cues) remain), the track are still readable and remain in their same file location.

Does anyone know how I get my previews back without having to reanalyse the files??

I'm on 6.5.3

cheers