Sorry to see that! It appears that our email provider, SendGrid, is currently experiencing a spate of serious account-takeover problems, which is probably causing some SendGrid-originated email to be blocked (often without even hitting your spambox). Here’s Krebs On Security’s writeup:
We’re working on mitigating this.
In the meantime, I would recommend signing up for an email service yourself (not SendGrid! Mailgun or Send in Blue, perhaps?), and configuring it as a Custom SMTP Server in Anvil’s Email Service. This will allow you to route around the damage for the time being.