Planes & origin missing from tree

One of our users created a part file yesterday and saved it.  When he opened the file this morning, all of the geometry was missing (no features in the tree), and the origin and default planes were missing.  The options to show the origin and default planes are set to "show".  No other part files are affected and opening the "corrupt" file on another machine has the same missing items.  The original file size is normally large but when saved to a new location, the file size is very small.

If it weren't for the missing planes and origin, I'd say that the file save got screwed up.  Since critical SWX design features are missing, I'm at a loss for what happened.

Just a corrupt file?  I'll welcome any opinions.

We're running SWX 2017 with a variety of SPs (2.0-3.0).

Thanks.

SolidworksParts And Features