Hi everyone. We’re shipping an update to revert the ability to choose a custom icon.
The reason we’re doing this is that the workarounds we used to implement this causes issues with other app functionality (multitasking) on some popular devices and launchers.
Unfortunately, the workarounds mean that if you have enabled a custom icon, and update the app to this version, then you’ll lose the ability to open the app! 
Please revert to the default icon before upgrading to the latest beta. If you don’t, you’ll have to uninstall and reinstall the app.
Sorry!