Multiplicity stop working for me ever since 1903 like many others have pointed out. 1909 is no go to.
Like many others...? I think there were two total that recently reported issues after a Windows update. Both of them had MP crashing (in their event logs) which is EXTREMELY rare and -in my experience- always caused by and outside app or setting.
I am on a 1909 general release box that is connected, via MP, to a Windows Fast ring box - one was upgraded from 1903 today, the other from a 1909 ISO - also today. Both not only worked flawlessly, I did not have to touch MP at all.
Knowing that, if you want to work on any issue you are having, I would be happy to help.
Stardock Support Manager