“Blank Title” notice appearing on mobile sites

When viewed on smartphones my site just reads “blank title.” It appears fine on the desktop. A user has to scroll down and manually switch over to mobile, but it’s not obvious.

I’ve deactivated and reactivated plug ins, I’ve disabled JetPack — is this a matter of switching to a more responsive theme?

Thank you kindly.

The page I need help with: [log in to see the link]