Looks like it’s been fixed. My oldest post is from March 13 and I can edit it now (which I couldn’t before).
@Amanda.Schade Also, there’s a bug with hidden posts & the activity feed: when signed in, I can’t scroll my entire activity feed anymore because it stops just before a hidden post; it stops at this post: Coming Soon: The Unreal Engine forums are leveling up! - #255 by midgunner66, where my post before it is hidden. When signed out, I can scroll the entire thing, so it only happens on the user’s account.