Yeah, I have issues with it as well, it never really worked properly for me, like ever.
I honestly think an auto-offline mode can easily become inconsistent, like recently when the server went out, people had different breakage symptoms, probably from having different files/data missing.
Apps like Spotify deal with this differently, allowing you to go offline mode using a switch as well. Just like Construct 3, Spotify has an auto-offline feature, and it is as inconsistent as the Construct 3 editor, however they mitigated the inconsistencies with a manual offline switch.
It would probably easier for the Construct Team to test if offline mode absolutely works or not by having this switch added since everyone will have the same outcome.