I work with PhotoShelter, Photoshop and Photo Mechanic. If I download a file from PhotoShelter and open it in Photoshop, the IPTC location field has the correct data in it. If I open the file in Photo Mechanic than close the file and reopen it, the IPTC location field data vanishes. If I then open that same file in Photoshop again, it is also gone.
All other IPTC Data seems to not have this problem.
To add a clarification, it's not the Data field "location" that vanishes but the data contained within it. The file I was working with was a JPEG and it was the Mac version 4.5 of Photo Mechanic. The Error is repeatable and only requires you to open the Info window then close it to make the information disappear. If you do not open the info panel and just import the image in it does not remove the data.