Mailgun is not sending password reset emails requested via API. No errors thrown. Laravel v5.6

I can not get Mailgun to receive password reset email requests through the Laravel out-of-the-box API.

When a user submits the password reset form, Laravel returns a success message to the user, but the Mailgun dashboard shows no emails sent, and no email is received by the user.

I receive no errors in Laravel and no errors are written to Laravel.log

Mailgun dashboard shows zero outbound emails sent from the domain, which leads me to believe that maybe it is not receiving the api calls??

The same issue occurs identically in my local dev environment on Mamp on my Mac, and in production on Digital Ocean with Forge -- both using identical Mailgun settings.

I am trying to work my way through the code to find the issue, an am stuck on where to look next.

When I log $notifiable from "public function toMail($notifiable)" in ResetPassword.php, i see that $notifiable has all the values it should have.

.env variables are set:

MAIL_DRIVER=mailgun MAIL_DOMAIN=.com MAILGUN_SECRET=key-...

Services.php is set:

'mailgun' => [
    'domain' => env('MAILGUN_DOMAIN'),
    'secret' => env('MAILGUN_SECRET'),
],

Mail.php is set:

'driver' => env('MAIL_DRIVER', 'smtp'), 'host' => env('MAIL_HOST', 'smtp.mailgun.org'), 'port' => env('MAIL_PORT', 587), 'from' => [ 'address' => env('MAIL_FROM_ADDRESS', '[email protected]'), 'name' => env('MAIL_FROM_NAME', 'Support'), ], 'encryption' => env('MAIL_ENCRYPTION', 'tls'), 'username' => env('MAIL_USERNAME'), 'password' => env('MAIL_PASSWORD'),

Guzzle is installed and composer is updated.

I have a fully updated version of Laravel 5.6 running on Digital Ocean, and locally on Mac. This is my second Laravel app running on the same infrastructure. The first app sends emails fine through Mailgun, running on the same Mailgun account, using the same API secret.

Can anyone suggest where to look next? Thanks very much!