The Happ server list is empty
The client opened and there are no locations. The usual failure is the subscription address or the access term, not a missing “app key”.
The whole link
Messengers often cut the end of a URL. Open the account on the same device and copy the subscription URL with the button, not from a forwarded chat.
Refresh and term
Pull the list down or tap refresh. In the account, check that the paid term is still running. Refresh does not repair an old vless:// line — you need the subscription link.
Next
If the link is intact, the term is live, and the list is still empty, write to support and say which device you used. A public channel is another stranger’s server.