I've found a hole that has a drop from highest point [207] down to [164].
Been working it for over 30 hours now and tried to fill it all around, dig all around, both 5 squares in all directions.
Used both normal, shift- and ctrl-clicking when digging and dropping dirt.
Had 3 people trying to solve the problem for several hours but it does not seem to work.
https://www.dropbox.com/s/oafk22ccfjwxxvu/bugged%20hole.png