SW 2017, SP 1.0

Really bizarre behavior I'm seeing.  When closing a part or assembly that has been modified (indicated by the * next to the file name), I am not prompted to save the changes and they are automatically discarded.  This is normal behavior of the document is read-only, but I am experiencing this with non-read-only documents.  I have to manually hit ctrl+S to save the document before exiting, otherwise all my changes are lost.

I've never seen this before.  I do need to update to SP 5 so maybe that will fix this problem...

Any ideas?

EDIT. Most of my projects are in 2016 so I just recently started using 2017.  I don't recall 2017 ever asking me to save.