Hi, markrob
In case you are trying to use secret key mode:
https://openvpn.net/vpn-server-resources/faq-regarding-openvpn-connect-android/
OpenVPN Connect uses the OpenVPN3 client library. While it supports almost all configuration directives, some are deemed obsolete or rarely-used. If you believe there is a directive we're not supporting right now, but should, let us know by opening a support ticket and providing the details there.
Here is a partial list of directives not currently supported:
...
secret — Static key encryption mode (non-TLS) isn’t supported.
...