> Sadly, the file loading option did not work. I tried a percentage of file, as well as last non blank frame, and pressing F3 brought no results.
Was that with multiple video files selected? If so, that's a bug that affects many people but for which no solution has been found yet.
The work-around is to select the files and press INS instead of F3. This will Tag the files, but in order to tag them, ThumbsPlus has to thumbnail them first, and then for some reason it will honor your percentage setting. To remove the tags, just press Ctrl-INS afterwards (with the files still being selected).