Strange Firefox Bookmarks Problem

[valdai]

So this is a really annoying problem, on certain bookmarks in my bookmarks menu, right-clicking + delete does nothing, so I'm just stuck with them taking up space there. Any ideas?

I'm sure this is just some stupid issue caused by myself but apart from actually going into my bookmarks files (cba to do this every time I want to delete something) I can't come up with anything.

 

[valdai]

Oh that's weird. Going into organise bookmarks I was able to delete it. Didn't think of that, thanks!

Seems odd though, any possible reason for this?