Yeah, I see it now, it was very subtle. There was some slippage due to the slowness of my computer, and I didn't swing in a wide circle. I was mistaking the slippage as normal, but I can see your bug now. I was also confused because if I added an anchor, not a media, there is no bug !!

Oh well, thanks for figuring it out, and will save the correction factor for later reference.

Once I understand why, it's completely logical ;-)

I'm glad someone knows what they are doing. :-)