While doing a search in LOTW I discoverd some of my entries were missing.
On closer inspection of the search window I found if I left a space ( just one letter ) on the left side of the window it would return a nil report.
I usually copy and paste a callsign into search window and dont be fussy where I place the callsign, untill now!!.
This has resulted in a few duplicates entered into LOTW.
So keep your callsign entry close to left side of search window.