Were you ever able to get this fixed? I am experiencing the exact same issue.
Yes, I figured it out after a lot of trial and error. Turned out that I was using "old" templates and every time I created a new invoice it defaulted to the old style template and the date column was missing. Once I changed the default to the "new" or "modern" template, voila, the date column showed up. I'm not real happy with the look of the new template, but that's for another day. At least now I can get dates to show up... Rob