Groove Agent Auto fill out of time

Running lastest Cubase 9, 64 bit windows.

When I use the Autofill option to introduce some extra fills and breaks, Groove will slowly go out of time with the Cubase tempo. When I switch this off again, it will reamin in sync.

I saw in very old release updates that this has been an issue in the past.

Is there a fix, or work around.