Well this is weird. In one of my accounts I had a discrepancy in the count so I laboriously typed them into a spreadsheet (why, oh why, did I not bother to record this info in Calibre originally

).
I had a few books in the new library screen that didn't have a download option but had the purchase price listed and highlighted.
I became very frazzled at the loss of a few expensive books until on checking Calibre and my receipts finding that one had been purchased from Amazon and one had been purchased from Google. Another I am pretty convinced I had looked at but had never purchased at all as I was waiting for a price drop.
The upshot is that I had *never* purchased these from Kobo at all
I think Kobo is being more Kobo than it usually is - and that's saying something!