Did you check the dates of the posts in this thread? You flew before this thread even started. The early posts in the thread say that it's not part of OW yet (as recently as December 22). It's only a post from Jan 10 (a whole two days ago) that says it now is.

Presumably, therefore, the change from not being part of OW to being part of OW occurred sometime between December 22 and January 10.

That doesn't mean, therefore, that flights "way back" in early December will necessarily count. It should, more hopefully, mean that flights in the near future will count.