What worked for me is to include certificates in the .ovpn file.
to do so I copy pasted the text from certificates into ovpn file and delete links to the file certificates:
ca ca.crt
cert client.crt
key client.key
*no "inline" reference is needed
certificates should be in the end of the config:
<ca>
-----BEGIN CERTIFICATE-----
XXXXXXXXX
-----END CERTIFICATE-----
</ca>
<cert>
-----BEGIN CERTIFICATE-----
XXXXXXX
-----END CERTIFICATE-----
</cert>
<key>
-----BEGIN RSA PRIVATE KEY-----
XXXXXXX
-----END RSA PRIVATE KEY-----
</key>