In CDG in F a few weeks ago I was initially refused Champagne on the ground. There was then a short delay, at which point magically a glass appeared.

It's not only QR, I've sporadically been declined on BA a number of times on the ground in F. At one point I tried to work out if there is a pattern, but gave up, it's consistently inconsistent, although I do think it has something to do with whether they have in bond/out of bond Champagne loaded. Sometimes, for example, you'll be offered the cheap stuff from J on the ground if they have no tax paid premium stuff.