I have a part that I'm about to revert to last week's backup (i.e., give up on) because it has not changed (in a good sense anyway) since a previous backup. However, it's causing some very odd erroneous appearance results. Simply put, this sheet metal part has some faces which are transparent when viewed from the from and not the back, and some other faces which are transparent when viewed from the back and not the front.

Why did this happen? How can I fix this?

I was not editing the part, but was editing one assembly it is used in (a shelter house subassembly for a very large assembly). Then the walls turn partly transparent. It is not a component setting in the assembly, it is actually in the part file. File is attached. (Edit: Note that this condition only exists in one Configuration for me, the current one as saved.)

References: 2016 SP3, Windows 7, NVIDIA Quadro K2200 with supported and up to date driver.

Thanks for any ideas. I'll go revert the library file to backup now and proceed abnormally as usual.