For whatever reason, I am unable to offset entities that were imported from a DXF vector file. I know that entities cannot overlap, but I tried an offset as small as 0.01mm and it is not working. I tried to check if the sketch was closed and was able to extrude it, so it must be.
Here is a screenshot of the issue. I wish to extrude the edges by 1mm outwards. The file is attached.