Same problem here. The code that breaks the "Configure options" functionality is
'MAIL' => [
...
'transport_smtp_stream_options' => [
'ssl' => [
'verify_peer' => false,
'verify_peer_name' => false,
],
],
],
But this only happens if the code is in the file settings.php. If you write it in the file additional.php, it should work.
$GLOBALS['TYPO3_CONF_VARS']['MAIL']['transport_smtp_stream_options']['ssl']['verify_peer'] = false;
$GLOBALS['TYPO3_CONF_VARS']['MAIL']['transport_smtp_stream_options']['ssl']['verify_peer_name'] = false;
I don't know exactly when, but this must have changed in one of the last versions after 12.4.11.