When you mention "shortened path", are you sure it's actually shortening the path? Most tools only show the full path while you're editing that field. Otherwise, they just show the file name.
For example:
Full value stored in the output: "C:\ProjectData\outputfeature.shp"
Display value when you don't have the output field selected: "outputfeature.shp"
The next thing to check would be whether you have the necessary file permissions to save a file into whatever folder you're targeting. If it's a University or similar large organization's server, for example, you might be trying to save outside the space designated for your user.
Also, while irrelevant to the topic at hand, anytime shapefiles are mentioned, I feel obligated to raise the suggestion to consider whether you need shapefile, or whether the requestor is using the term in the generic "GIS data" sense. See https://switchfromshapefile.org/ for more information on the ups & downs of shapefile in the modern GIS ecosystem(s). That link is often slow to update its security certificates, so if you get odd warnings and don't feel comfortable, try back in a few days.
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M Reed
"The pessimist may be right oftener than the optimist, but the optimist has more fun, and neither can stop the march of events anyhow." — Robert A. Heinlein, in Time Enough for Love
