After a sequence of highly targeted IC leaks, General Flynn has just resigned citing that he "briefed (...) with incomplete information". Resignation letter:
https://pbs.twimg.com/media/C4mQam8VYAAXeMi.jpg:large
This can be taken as a confirmation he did discuss sanctions with the Russian embassy. Let's hope there will be a proper investigation in who-knew-what now that "executive privilege" can no longer be cited as a reason not to investigate.
The question that remains for me is this: If Flynn only discussed sanctions with the Russian ambassador as per courtesy, and nobody else in the administration knew, why not simply release the tape recordings of those conversations in redacted form and keep Flynn on board?