How can I reenable Gmail notifications after disabling them through Inbox? I used to have both Inbox and Gmail installed. This meant duplicate notifications. Inbox had the option "Turn off Gmail notifications" which I had selected. Since then, Inbox has become defunct and I haven't been able to figure out how to undo that.

Crucially: all of my Gmail and Android settings turn notifications from Gmail on, but they still won't show up. Does anyone know what Inbox did and how I can undo it?
You have removed Inbox app, but the issue remains. If Inbox did modified Gmail settings, then you have to tried the "usual" steps:


Clear Gmail's cache.
Clear Gmail's data (this step also clears the cache): It will reset the app to default. You will have to login again to your account as you did the first time you used the app.
Remove and re-install Gmail (if it was not installed by default like in some custom ROMs).
Remove all Gmail updates (it will allow Gmail to return to the state it had when you bought the device).