Nope, not a bug. Your PM ability has been restricted due to not having 10 counted posts on the forum. Basically any account created after July 21st, 2021 got this restriction, however we are slowly getting to the older accounts with less than 10 counted posts and manually removing the access until you reach 10 posts. When the updated ruleset was put in place, prior accounts got grandfathered in. If you manage to make 10 posts (excluding fun and games, profile posts, and group posts) on the forum, you'll get your ability to PM back.