I have found that sometimes you need to clear Xcode caches in order for Quick Help to start working again. For reference, I am using Xcode 16.2, and what I see matches the lower, dark-mode image you posted above.
I think that you are correct. Maybe the older version of Xcode would show the help from the virtual function when you are clicking on the override function. That is not working for me either, in Xcode 16.2.
I find that since XCode 26 the indiexing of projects is much worse than bfeore. “Jump to definition” works some of the time, but half the time just pops up a “?”.