It's an experimental feature and will be subject to such quirks and issues. I would not advise using experimental pre-release features in a classroom environment. We made it opt-in to try to avoid people relying on it because we know it will be a rocky road. Something to bear in mind for future.
In this case because of Google's origin trials system, occasionally we have to renew a trial token and it means you have to clear your cache and reload Construct to get the new token and get the feature back. Or you can just use the latest beta release (but I wouldn't recommend that in a classroom environment either for the same reason, it's still pre-release quality).