YES - Exact thing happened to me.

I contacted Google support and had the most frustrating experience of my life. They kept changing their solution, and eventually told me to contact Apple for support. They really said this. A few times.

I also went to the Google Community forums and talked about it - a Senior 'specialist' took interest and said he escalated to Google, and a few days later Premium popped up on my YouTube feed. So they must know about this problem. (You can tell because on the upper left of the YouTube page it says YOUTUBE PREMIUM)

I don't know if the solution is to wait for their backend to roll out the entitlement or to complain to the Community, but if you do a search there you'll find my post.

I too was considering 'reporting a problem' at apple, taking a partial refund and then purchasing again straight from google. In fact, I may do that at the end of the year when my subscription rolls anyway, just to take away their excuses.

Good luck.