Mike you exited play mode and immediately hit compile, if you were watching it showed compile completed in ~1 second. Of course you’re going to run into errors. Give unreal at least half a second lol. Programs will sometimes make something available before it can be used but it is not fully implemented/ready depending on load order.
Unfortunately it seems Unreal has coded the play button so it has to wait for compiling to be completed but not the compile button to wait until the play session has been closed fully and it’s actually ready to compile.