I observed the same trend as well. My immediate thoughts are that "mortgagee auction" units still carry a certain social stigma to it. HNWI and UHNWI do not like going around telling people how much below market value that they managed to secure their units for, or securing it in a high profile manner, least of all in a public auction. Most prefer purchase via private treaty with no caveats lodged for privacy.
This is the smallest of the PHs and the developer is still marketing the rest. I think that 1150-1200 psf is achievable for this unit as the non-livable foot print is substantial. It's obvious that the original buyer overpaid for the unit. Bank is not very urgent as there is still equity in the unit.