CVT transmission noise and engine load

[blitzracing]

I had a minor issue on a recently purchased Honda S660 with a CVT gearbox. When the car is first started and you go from Park to Reverse, there is a noise like belt squeal for a few moments and the engine RPM drops. I can understand the RPM drop as the engine load increases as the auto box adds load in "gear", but I cant fathom what's slipping. The two external drive belts don't drive anything in the box- I think just water pump, aircon and alternator, and this load wont change significantly in or out of gear. This leaves the gearbox internals, and the CVT steel belt, but its all oil lubricated. I've checked the gearbox oil level and that's correct. It does not do it again until the engine is fully cold. Any ideas from the hive mind please?

[GreenV8S]

I don't know how that CVT works, but presumably there's something in there to allow the transmission to slip when it's idling in Drive. Maybe a centrefugal element? Perhaps the cold idle is just high enough to make that engage a little?