Did you by chance launch rig manager without the KPA turned on, then connect the KPA later?
i did that today and notice that i had to relaunch rig manger with the KPA already on. If i turned on the KPA after rig manager was launched, i couldn't get the preview to work with clicks or double clicks or any combination. After shutting down rig manager, and launching again to make sure it saw my KPA, then the preview worked as before. I'm on MAC OS