Had the same problem then I found this error in /var/log/openvpn.log
Code
Wed Jul 18 11:46:23 2018 MYIP:46585 CRL: cannot read: /etc/openvpn/pki/crl.pem
Wed Jul 18 11:46:23 2018 MYIP:46585 VERIFY ERROR: CRL not loaded
so I did this in SSH and it works now.
Bash
chown nobody:nogroup /etc/openvpn/pki/crl.pem