That seat looks damaged to me; the second pic seems to show a mark just above the place where the corner of the seat either has something in it or was not square to begin with.
The first pic seems to show a ridge about 2mm above the flat ending in a similar mark, and it might be in the second pic as well.
I wonder if a race-too-small was attempted once, making the mark and the ridge, then was removed and a race on the proper size fitted.

Some crown races have a relieved section just above the flat face, to allow for bad seat corners.
If you had such a one and then tried a race without such relief, it might well stop short of the bottom.