Thanks for your help and suggestions....

Two photos, one external one internal.
External - replaced photo with one already used - no change.
External - removed ‘hidden’ from title - photo could be seen.
Internal - removed ‘hidden’ from title - photo could be seen.
External - replaced photo with original - photo could be seen.
Both - reinserted ‘hidden’ in title - both photos could still be seen.
Maybe there was a corruption in the titles, nothing else makes sense.

Thanks for your reply.
I’ll try your suggestions and report back.

First post so please excuse anything I get wrong....
Been using Juicebox-Pro for over four years without any problems but now i have one which I can't solve.
Image source is Flickr but two photos show as blank. In the builder the thumbnails and main image can be been seen, when published the thumbnails can be seen but not the main image. I have tried various browsers.  The photos have been processed the same way as all the others.
The gallery can be seen at : http://www.gwise.co.uk/Juicebox/Jb-London/index.html
Ironically they are shots of a hidden cafe. Any advise appreciated, thanks....