The necessary ports must also be opened for LND. These are 8080 for the REST API, 9735 for connections to other Lightning nodes and 10009 for the RPC API.

sudo ufw allow 8080 comment "Port for LND REST API"
sudo ufw allow 9735 comment "Port for LND P2P connections"
sudo ufw allow 10009 comment "Port for LND RPC"

It is important to also open port 9735 on your router and forward traffic to your Pi. For the other two ports, this is not necessarily necessary unless you want to communicate with your node from the outside.