Fiberworks for Mac is not able to directly save a weaving draft as a WIF file. Fiberworks files by default save as a "DTX" format (the file name ends with ".dtx". If you have the Fiberworks for Mac software and want to be able to load drafts saved as a DTX into TempoWeave, you need to save those as a standard WIF. Note that Fiberworks for Windows does not have this issue, you can directly save as a WIF file.
The workaround posted by Fiberworks is covered in this YouTube video:
