Well, I am getting nowhere trying to update my 'Make-an-Offer' listings in bulk, so decided to turn the feature off en-masse... all 1613 listings... but there were 4 fails... and I couldn't search for these independently - doh! - I had to trawl through each page (33 of 'em) until I hit upon them...
And the reason for the failures? - they had recieved an offer already... but... the offer was auto-declined and therefore no longer valid, so why can't I take it off?
I guess I'll just have to close/edit/relist to get rid of the 'Make-an-Offer' option... support will be contacted.
TTFN