As far as I can tell it is finished indexing, still looks the same. Most of the files under documents are in fact Photos. However they are mainly in various RAW formats. Sigma .X3F, Nikon .NEF, Samsung .SAM
so maybe High Sierra doesn't recognise the as Photos. Not a big deal.
Thanks for your advice
Booted back to El Capitan and both partitions contain the correct info. So it must be an High Sierra thing!!