Sync Clipboard works unreliably

I find that the Sync Clipboard works very erratically. I have a computer onwhich it never works. I have a computer onwhich it sometimes works. And I have a computer onwhich it works reliably. I have been unable to find a solution for this issue. 

I have checked whether the option is selected or not, and I have cycled the selection from off to on again.

I have tested different browsers.

I have used the Client.

I have uninstalled and reinstalled the Client.

I do not know what else to do.

I am a user of paid LogMeIn Pro. All of the computers are now running Windows 10 Pro.