Seems like the post about virtual partner issues got deleted from the forum today after I updated about it not working in the latest software release either. (Not being able to update the target pace).
But I did some more testing, and found that the virtual partner screen in the run app has a bicycle symbol on it. I went to the bike ride app, and changed the target speed in the virtual partner screen there. That updated the value in the running app as well. This works fine as a workaround for me, as I rarely ever need the virtual partner for cycling anyway.