1.1.6 functioning but not reporting true for credentials

We setup the plugin as per usual.

After OAuth Server confirmation we get the “green” interface.

Test email, works – expected.

Plugin message :
Gmail SMTP plugin cannot send email until you enter your credentials in the settings and grant access to your web application.
Test email, works.

Test from site, works – not expected.

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Further info :

When setting up a fatal error occurred. It seemed that the ‘client_id’ value was not being passed. Checking the POST payloads it seemed to be OK. Retrying the process solved that issue.

PHP error log :

[07-Dec-2017 07:57:41 UTC] PHP Fatal error: Uncaught InvalidArgumentException: missing the required client identifier in xxx/wp-content/plugins/gmail-smtp/google-api-php-client/vendor/google/auth/src/OAuth2.php:635
Stack trace:
#0 —/wp-content/plugins/gmail-smtp/google-api-php-client/src/Google/Client.php(340): Google\Auth\OAuth2->buildFullAuthorizationUri(Array)
#1 —/wp-content/plugins/gmail-smtp/class.phpmaileroauthgoogle.php(65): Google_Client->createAuthUrl()
#2 —/wp-content/plugins/gmail-smtp/main.php(155): GmailXOAuth2::authenticate()
#3 —/wp-includes/class-wp-hook.php(286): GMAIL_SMTP->plugin_init(”)
#4 —/wp-includes/class-wp-hook.php(310): WP_Hook->apply_filters(NULL, Array)
#5 —/wp-includes/plugin.php(453): WP_Hook->do_action(Array)
#6 —/wp-settings.php(450): do_action(‘init’)
#7 —/wp-config.php(183): require_once(‘/home/a1 in —/wp-content/plugins/gmail-smtp/google-api-php-client/vendor/google/auth/src/OAuth2.php on line 635

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Removed all plugins. No difference.

Any help or advice would be appreciated.