There is a bug that appeared in Gallery Server Pro 2.3.3456 released last week. I just fixed it and updated the download packages to include it. I didn't rev the version number because that takes a few hours and this didn't seem important enough to justify the effort.
This affects those of you who disable the image metadata feature, as seen here on the Media Objects - General page in the Site admin area:
If you kept this option enabled (which is the default), you are not affected by the issue.