Dylan, comparing the grid entries available against the answer lengths shows an additional 2 10-letter entries (fair to assume that these are the unclued entries), an additional 6 7-letter entries but 12 less 6-letter entires. So might the non-conventional entries be the extra 12 6-letter answers ? Look carefully at the 6-letter answers you have, and although this is a rectangular puzzle, it might help if you think in terms of radial puzzles for the non-conventional entries.