Excel Sort is broken

I have no idea how this problem happened.  I have an Excel spreadsheet that's just under 500 lines long.  I keep dates and times and hours in it.  I enter the data one new week at a time at the top.  I occasionally grab a block of a few weeks and copy it to the right and then sort by date to change it from newest first to oldest first.

This has always been a no brainer.  Very easy to do.

Today, it didn't work.  Furthermore, trying to reverse sort the previous blocks of data, which I leave hanging around on the right, is no longer working.

I went through the update process to see if I somehow missed something. Also, I don't use any add-ins.

Again, doing a sort on something which sorted days ago no longer works.

Has this broken for anyone else?