Thank you Steven, that solved the problem!

While the home gallery displays all 162 photos, when I click "expand gallery" there are only 50.
Small screens also show only 50 photos.

I upgraded from Juicebox Lite and there is a second gallery on the same page created with Lite. Might this be the problem? The new gallery (with 162 photos) was created with the Pro version.

This is our page:
http://www.metmeetings.org/en/photos:931

Many thanks in advance,
Emma