This happened to me recently and I solved it by switching back to Youtube Classic using the icon of someone walking away, down at the bottom.

That fixed the problem, but now I don’t know how to switch back to the new look (which seems to have a very big player). I like the classic interface but wanted to switch back to the new one and see if the comments are fixed for it too, and just to compare them.

So anyway it might be worth a try if you don’t mind getting stuck in Youtube classic, or if you have a way to get back again somehow.

I must admit I find the youtube interface very confusing at times: Why is the Youtube interface so bewildering?