Can't Use Custom Dev Client Offline

I created a small test project just to see what the custom dev client was like. Ideally, I’d like to create an app that uses RN Firebase, specifically for its support of offline data. My test app includes RN Firebase, and a button that does a simple query from Cloud Firestore. I run the query once to make sure that the data is cached locally. Then I try to run it again to see if it will get the data from cache (as it is supposed to do), but first I put my device and/or simulator into offline/airplane mode. Cutting network connectivity immediately causes the app to lock up and revert to the splash screen. Sometimes I get an error on the device that says that it has lost connection to Metro.

On the (physical) iPhone, the app will have become completely locked up at this point. Even if I restore network connectivity, the app does not respond, not even to shaking it in order to try to get the dev menu. I get similar behavior on an Android simulator.

Is this the custom dev client experience? Is there no way to test offline mode? Or is there some secret setting that I was supposed to know about, but which wasn’t really documented anywhere obvious?