drag and drop uploader not working from any browser with Mac OS

I've finally decided to write the forum to see if anyone might have a suggestion. I have been a smugmug user for years and have never had such a consistent problem with using the drag and drop uploader tool.

I am having a problem on multiple Macs running Mountain Lion and Mavericks and using multiple browsers including: Safari, Chrome, Firefox.

I can get the uploader screen to display and I can drag files (JPEGs) onto the window but then no progress happens. The screen just sits idle with no progression on uploads.

I tried it with the same files from my Windows 7 system with Firefox and IE and it works just fine. I can drag and drop files and the progess bar immediately is displayed and the files are uploaded.

I know I can try and extension to Lightroom or iPhoto but I would like to use drag and drop again for simplicity.

Help!

thanks,
David