I just read the 2018 decision: SCO GROUP, INC. v. INTERN | 879 F.3d 1062 (2018) | 20180102045 | Leagle.comThe only case I am aware of in the United States that is on point is SCO vs. IBM and that was about the GPL. SCO (or the previous company they bought the IP from) for a time offered Linux under the GPL along also contributed work to Linux. And this happened to incorporate the IP they were fighting about. But SCO tried to say that they deauthorized their contribution. And ultimately did not win their point.
But to be clear this was a messy, messy, case and this was just one of the many IP issues they argued about.
As far as I can see, it says nothing about the workings of the GPL or CC licence. It seems that SCO lost their claim to copyright, and that Novell who won on that point did not go on to assert any copyright infringements.
The only case I've read directly on point is this one - Great Minds v. FedEx Office & Print Servs., Inc., 886 F.3d 91 | Casetext Search + Citator - and in this case the court narrows the effectiveness of the "automatic offer" provision, though not in a manner that I think would be relevant to the issues that would arise were WotC to purport to withdraw its offer.