Thank you for posting @humphrey , I am happy to assist!
I reviewed the known cases of the reset password emails not being sent, and this is the info I came upon:
As mentioned on Configure Custom External SMTP Email Provider you will have to configure your provider to allow inbound connections from Auth0. To see the list of required IP addresses, as you are a Public Cloud customer you can navigate to Auth0 Dashboard > Branding > Email Provider or from Auth0 IP Addresses for Allow Lists
Could you please double-check if your affected Auth0 tenant is all set in terms of Auth0 tenant ↔ email provider communication?