When you use the VST3 360pan suite plug-ins in Reaper you will have to verify two settings in Reaper's preferences are properly set up, else the suite will not function properly.
In Reaper choose Preferences... from the bottom of the Options menu and then first go to:
1. Audio -> Buffering
and then TURN OFF the Anticipative FX Processing
this will ensure the 360reverb to function properly (else you will get sync problems)
2. Plug-Ins -> VST
Under VST Compatibility please set the Parameter automation notification to:
Process all notifications
this will ensure automation is written to track when you control the panner pucks from the video overlay (without the panner plug-ins being open).
3. Editing Behavior -> Automation
When recording automation and stopped should be set to: Do not add additional points.
This to ensure you can nudge the time cursor and then drag pucks and write automation this way (like in the tutorial/example project).