Running into the same issue and it’s basically blocking us from testing our web pixel before deployment. The current work around we’re using is to code the web pixel in the app, and then copy/paste the code into a custom pixel in our development store, replacing all the settings fields with the expected values. We can’t test that the install works (we’ve changed the settings fields so it won’t install at all anymore because it thinks they shouldn’t exist), but at least we could move forward in developing the pixel itself and testing it with the relevant events.