I'm posting here in case anyone has any news on this issue.
I installed Xcode last night and I'm seeing this issue as well. I'm not seeing results automatically in the sidebar when I add code. I do see results in the sidebar as well as in the Debug area if I click on "Execute Playground", but results from new code after that are not automatically added to the sidebar. Live View is on, and switching it off and on again doesn't help.
MacBook Pro (16-inch, 2021), Apple M1 Max
masOS: 12.1 (21C52)
Xcode: 13.2.1 (13C100)