For some reason I can’t reply to that thread. It’s still not fixed. The thumbnail gallery button now appears on my post/page editor, but when I publish the page it’s blank.
I’m not clear on the instructions am I supposed to permanently disable W3 Total Cache? I thought this is something important thing to have. Anyway, I disabled it and cleared my browser cache. And nothing appears on the published page.
I tested it by opening the page in a different browser, still nothing.