I believe if you are using VPN, then you must use remote port forwarding. The port that comes from the VPN service is different from the default listening port, so you must manually set the config to that particular port. Anyway, AFAIK, even if you did that, other nodes will not prioritize making a connection to you since you did not use the default port.

About your whole issue, I don't actually know how it works, but I don't know if a brand new node immediately gets an inbound connection. My Tor only nodes only get an inbound connection after I leave it ~20days, after that, I also can verify it on Bitnodes.