Multiple tags not separating--how to fix?

I have three bookmarks with multiple tags that come up as one tag. For instance, one has the tags "email" and "scams," with the comma and space between them, as I have on my other bookmarks. However, instead of separate tags for "email" and "scams," I get one tage that says "email, scams," which isn't what I wanted to do. My other bookmarks work fine, with separate tags. What's wrong, and how do I fix it? (By the way, I tried deleting all the tabs except "email" to see if that helped; I ended up with four separate "email" tags, one for each of these three bookmarks and one for the rest with that tag.)

Thanks.