1. Units
One reason a DXF file does not uploading could be the units for the file.
DXF files with the INSUNITS set to mm tend to upload successfully. The drawing units (DWGUNITS) can still be set to inches but the INSUNITS need to be set to mm.
Here's how to edit the INSUNITS value for your design software:
2. Large number of Points
Very large files can be a bit overwhelming to calculate cut time from. If your file has multiple parts, or technical drawing data that is additional to the top down line drawing of your part, try saving them out separately to reduce the file size.
3. Dxf version
2007 dxf files tend to be the most compatible version between sofrwares, if you haven't already saved out as this type and you are able to, please try a 2007 dxf