NoMoRobo blocked a "Verified" call

I use NoMoRobo with my Comcast/Xfinity landline. Today we had a call from medical provider that we needed to answer, but it was blocked by NoMoRobo. In the Xfinity Voice web page, "Call History" tab that is a log of incoming and outgoing calls, this number shows as "Missed: Verified". Apparently NoMoRobo blocked the call after 1 ring, as the log also shows that an outgoing call to (202) 813-1600 was made at the same time, which means Comcast/Xfinity forwarded the call to NoMoRobo. 

Why was a "Verified" number, which should have been passed through, blocked?