Put a case into ESRI support today on this. Indicated would proceed to discuss this functionality on the new map viewer with the internal team before further action. @KeithGanzenmuller
Not sure how folks are coping without this for so long. I haven't transferred to that viewer yet much for a variety of reasons, but I was surprised that it wasn't an option.
EDIT: Figured a workaround. Must be setup in Classic first. And then it transfers into the new map viewer.