Configuration seems OK to me.
Debugging Nonce::verifyNonce()
I noticed:
self::getOrigin();
returns 'https://somedomain.org:443'
self::getAcceptableOrigins()
returns array('http://somedomain.org', 'https://somedomain.org')
Thus, the returned origin is not found in the acceptable origins array.
Note the missing ports in the acceptable origins.
Matomo version 3.13.6.