Hi Steven, I have more or less the same problem. Suddenlyall my galeries that I published for3 years do not appear when I am connected. Thumbs are black and the pictures do not appear. The galeries work fine on local, but not on the web. This happens only with my computer, not with another computer. I did not change anything in my process. I am on Mac OS El Capitan.
Can you please help me?
I send you a link on one of the galeries:
http://www.helenebarnaud.com/BLOG/GAL_NEW_ZEALAND_3/

Thank you
Helene