When I originally followed along with the lecture and set my Blueprint game mode as the default game mode in the project settings, clicking play still showed the BaseGameMode and DefaultPawn. I went back and verified it was still saved in the project settings. I had to save everything and close the Unreal Editor and open it back up again. When I opened the project settings all my default game mode and even default map mode values were gone. I had to set everything again and then this time clicking “Play” showed my changed settings. I tried closing the Unreal Editor again and reopening and verified the settings did “stick” this time and didn’t have this issue again. I’m running Unreal 4.26.2.