The only way I have found to fix this is to restart the phone. Clearing cache or force restarting the app does nothing to fix the problem.
Authenticator sometimes starts with a black screen.
Sometimes I get a black screen when I try to open the app. Eventually a system message comes up stating that Authenticator isn't responding and I can close the app or wait. Waiting never ends up showing the landing page. Closing the app and restarting doesn't resolve the issue either. I can reopen the app right after force closing and the same thing happens. Eventually the app opens without issue but it can be upwards of 10-15 attempts before it works properly. I've tried completely reinstalling the app and also clearing data and cache. Nothing has resolved the issue. It's very frustrating to need 2FA for nearly every login these days and have an unreliable app. A bunch of recent reviews on the Play Store describe the same issue so it's not isolated to just me. I also joined the beta but that failed to resolve the issue so 6.2408.5757 still has the issue along with the current public release.