I thought I’d just give an update on progress. Hopefully this may help anyone else who is wrestling for control of their Nova (or Star or Atom). I tried the Clear Image Cache followed by Rebuild Database. After quite a protracted period of processing it returned to exactly the same state as it was before. Alanis Morrisette still looked like Adele - Sting still looked like Eva Cassidy etc.
I then went away for a few days so switched everything off at the mains. Upon my return I fired everything back uo and - SHOCK HORROR - everything had disappeared from the server. There were no pictures, no albums, nothing! I could could still see the albums in the USB source - but no pictures. I tried all sorts of things to get back to the way it had been before I went away - but nothing seemed to work. I was lapsing into a deep depression when suddenly, just by chance I stumbled on the solution. I had been going through all the settings in the app when I tried switching OFF server mode. There followed another long period of processing when lo and behold - the server came back complete with all the pictures. The half dozen or so wrongly allocated pictures are still there but otherwise it’s all working well. Phew! What a relief!
I hope this helps anyone trying to do the same thing. I’ll let you know if I get the last few album covers sorted. Happy New Year everyone!