Cloudflared not initiating rdp connection through Argo Tunnel

Trying to reach a server with rdp through the Cloudflare network. We use the linux appimage on server and client and this tut: https://developers.cloudflare.com/access/rdp/connect-rdp/ . But when running:

cloudflared access rdp --hostname monday.example.com --url localhost:8081

on the client it only says “Started listening on 127.0.0.1:8081”

No browser window is opened nor is there any url posted on the command line.
Looking at the network traffic cloudflared does not seem to initiate a connection to the Cloudflare network at all. However, when using other commands the daemon works, so not a network issue. Any ideas for troubleshooting?