In Inventor drag the red End of Part (or End of Folded for sheetmetal) marker to the top of the browser hiding the part in the graphics window to reduce filesize.
Save the file with the EOP (or EOF) in a rolled up state.
In Windows Explorer right click on the filename and select Send to Compressed (zipped) Folder.
Attach the resulting *.zip file here.
Or zip the STEP and attach it here.
Usual problems - thickness is not uniform or no bend zones or thickness not set in styles (but it sounds like you set that one).