[MM3-users] Function "Mass subscription" does not allow any more the format `"Givenname Familyname" <mailaddress>`

Wheras my older lists handled these format apparently correctly, I now cannot add any more

"Givenname Familyname" <mailaddress> ; or Givenname Familyname <mailaddress>

In any of these cases, only the part <mailaddress> is added.

Is this strange behaviour know? What can be done to have the correct function back to working again?