Last time I was trying to send custom named values to QGC it was necessary to make a custom version of QGC that knows about those different names for it to be able to use them. It seems it still has a predefined list of them, so I’d assume that’s still required.
That image looks like a normal NAMED_VALUE_FLOAT to me, just not the specific one you’re trying to send. That one is apparently from ArduPilot’s wind vane library.
MAVLink has various messages that are used for multiple devices / data sources, and a live viewer of MAVLink messages is not great for differentiating those. Granted if it’s not changing at all then your messages aren’t being received by Cockpit, but that will be much easier to see if you check in Cockpit’s Tools / Data-lake, and search for “NAMED_”, which should show you any and all named values being received, differentiated by their name.