Can't combine JPEGs into one PDF

I just updated my Acrobat to the Pro DC version and suddenly I can no longer combine mutiple JPEGs into one PDF. 

Here is what I am doing:

1. Save out a few files from Photoshop as JPEGs

2. Click File/Create/Combine Files into a single PDF (this is how I have always done it)

3. Click Add Files

Only some JPEGs can be opened while others cannot.

I also tried to create a PDF portfolio but after I add the files and create the PDF they are not visible. Clicking the Open button reveals a box that says that Adobe cannot open the file attachment because your PDF file attachment settings do not allow this file type to be opened.

Any help would be appreciated.