There have been 3 instances I've seen so far (Citco 6/15, Hitachi Energy 6/27, Taulia Inc 6/30) where an Excel-based project is exported to Source and in the zip file, the exported file is in Word format.
At the first occurrence of this, I reached out to Support who were easily able to help the client resolve the issue by showing them how to check the source file and move it out of Draft status.
For project exports, it might be useful to have a pop-up warning under the following conditions:
If the source file is Excel
If the Export type is Source
If the source file is in Draft
with a message similar to "Your source file is in Draft mode. This may cause the export to be in a different format. You can import the file at Menu - View Import Configuration before exporting."