Is it a bug or it does require a diamond membership?
From what I saw examining the updated membership plans, it seems only the lessons in the "beginner" section are available to people with a Gold membership.
Yesterday I actually completed one lesson from the course 7, so the first at the intermediate level.
I didn't know yet there was any kind of limitation, so today I tried to view the next lesson and got the upgrade window.
That's how I discovered about these "changes".
I would have preferred they had put a limitation to the number of lesson in a day, or a month, or whatever. Instead with my Gold plan I can access just the lessons I'm not very interested in.
Gold membership should be renamed to Bronze to be more realistic.
I don't like this decision, so I'm going to vote with my wallet and cancel my paid membership and keep the free one.
edit: you can read some comments about it here:
https://www.chess.com/news/view/a-new-years-resolution-improve-your-chess-with-new-lessons
I have a Gold Membership and after completing 1 lesson it is asking to upgrade, meanwhile I did not complete any other lessons. What can I do?