Thanks for the prompt response.
Nothing in the log.
Maybe I can shed some more light.
This address was the first I tried when I integrated KNX.
I played with it, trying different types.
Then I added the rest of the addresses, had a duplicate, deleted it, and since then I cannot get it to work
BTW, when I change it in YAML to 3/0/147 (non existant address) it sends the telegram. Changing it back to 3/0/47, makes the entity red again.
If you change address: it will create a new entity. The old one will be orphaned and can be deleted. This address of a switch is a “significant address” and is used as part of unique id for the entity. See https://www.home-assistant.io/integrations/knx/#duplicate-entities