Had HDHP all year with Medicare Pt A in Nov and Dec.If I choose "None" on "type of HDHP coverage for each month of 2018" TT says my coverage lapsed. Do I mark Self Only?

This section helps you figure how much you can contribute to your HSA (which you can't do while you are covered by any portion of Medicare).  I was covered by my HDHP all year--just didn't contribute to my HSA in Nov and Dec after I turned 65 and was on Medicare Part A.  All legal and appropriate. But TT is assuming I wasn't covered by my HDHP anymore--which isn't true. If I follow the instructions and say "None" the program correctly shows the limits of what I could contribute to the HSA but says my insurance coverage lapsed--which isn't true. If I ignore the instructions and check "Self Only", then I feel like I'm not truthfully saying that I was on a part of Medicare part of the year. No matter what, the program isn't letting me tell the whole story. I won't have a problem next year 'cause I'm changing insurance and won't be on a HDHP.