I'm using the FF 29.0.1 on Windows 7 and the tagging is working.

What is your operating system?

Thanks for replying. I am running v 29.0.1 on Windows 7. When I open show all bookmarks, select a bookmark, I add a comma after the last tag and enter a new tag. On the left panel, under tags, it doesn't create a new tag. It adds it to the existing tag like it's all one tag. FF seems to ignore the comma separator.

Silly me. I found the problem. I selected a tag from the left panel, tag drop down. Then I added a new tag. That only renamed the tag. I needed to select a bookmark from the right window first then add the tag.