Thanks to some help from @brighter1085293 I found an answer for you. The pharmacy is responsible for sending a correctly formatted Part B claim with both your Part B ID and your supplement plan ID. Common problems are your supplement plan is missing or incorrect on your CVS profile, the COBA (Coordination of Benefits Agreement) ID number is missing from the group field or the checkbox to bill the secondary is deselected.
Thank you for more info on this. I’ll put these items on my list to make sure another pharmacy does them.
I can’t believe my last CVS pharmacy told me they CANT send it thru Part B because Part B is for MEDICAL!