If on either PC, in Windows Event Viewer, you are seeing Multiplicity crashes that resemble
Faulting application name: Multipl2.exe, version: 3.0.0.0, time stamp: 0x52af40db
Faulting module name: ntdll.dll, version: 10.0.22621.2428, time stamp: 0xa899597e
Exception code: 0xc0000374
Fault offset: 0x000ed3cf
Faulting process id: 0x0xF560
Faulting application start time: 0x0x1DA05A7CDD9FC61
Faulting application path: C:\Program Files (x86)\Stardock\Multiplicity\Multipl2.exe
Faulting module path: C:\Windows\SYSTEM32\ntdll.dll
Report Id: a2e022be-2010-45bf-8150-1a0f1fb3ffc5
Faulting package full name:
Faulting package-relative application ID:
Please try the following
Windows Clipboard Sync
Please disable Windows Clipboard Sync on all PCs where Multiplicity is installed
https://www.thewindowsclub.com/enable-disable-windows-10-clipboard-sync-across-devices
MSI Afterburner \ Riviatuner
If you are using either product and their respective overlays, please disable them.
For more information on this, please see:
https://forums.stardock.com/493492/get;3900663
Purging and Reinstalling
If all else fails, please purge and reinstall the products on each PC
https://support.stardock.com/space/SHC/1347158073/Multiplicity+purging+and+re-installing