UPDATE
I had used QLE to edit a quicklist for a Chromium app (Google Calendar).
The Chromium generate desktop file was on my desktop and not in the usual location for launcher desktop files, if that matters.
I removed the Google Calendar App desktop file from the Ubuntu dock like thing on the left hand side of the screen and QLE began working again.
UPDATE
I had used QLE to edit a quicklist for a Chromium app (Google Calendar).
The Chromium generate desktop file was on my desktop and not in the usual location for launcher desktop files, if that matters.
I removed the Google Calendar App desktop file from the Ubuntu dock like thing on the left hand side of the screen and QLE began working again.