Problem Importing Grid - Corners.inp

I have tried to import a grid based on a manually calculated corners.inp file. The file does not import correctly. I then copied a corners.inp file from an existing model and imported into a new model. The same error occurred. One box is shown that encompasses a very large area.
I noticed that this problem was discussed in the forum under an older version of EFDC_Explorer. I am currently running EFDC_Explorer 7.2. The solution on the previous forum response was to use DELFT3D to generate the grid. Why is this still listed as an option in this version of the model?

This appears to be a bug. We will look to correct it an upcoming update for EE7.2. Thank you for alerting us to it.