Remote connect from dual monitor Mac to dual monitor PC

I have many users connecting to their dual monitor office PCs (Windows 10) from dual monitor home PCs  - myself included -without difficulty.  I just enable Multi Monitor in display options and then drag the two resulting Logmein windows to each of my home monitors.

I have a new user with a dual monitor Mac at home and she seems unable to get the multi monitor functionality to work.  Any thoughts on what the problem might be?