Issue with Onkyo receiver

I’m not sure when it happened but HA can’t control my Onkyo receiver any more.
I can browse to the IP address that’s configured in the HA config and the web UI is displayed.
I can ping the receiver.
Nothing I do in HA has any impact on the receiver.
Any ideas?

And as soon as I clicked the Create Topic button it started working. Isn’t that how it always is?