I am using the version that works on FF 52.6 ESR. This would be a 5, except that it will sometimes delete most of the many entries in it. One time at least it was because I hit "edit..." and then cancelled that edit without changing anything, and then hit OK, and then the next time i invoked it to paste text then a whole lot of entries were gone.
And when i imported a saved backup, then although it showed them all before the operation was closed after i clicked "Finish", yet after i hit OK on the next window to close it, then the next time i invoked it they were not there.
i found that you must import, then hit "Finish" and then hit cancel on the next window. Then all the imported entries showed up.