MAME/Flycast Outputs not working

*Specifically referring to device outputs, not display output.

I’ve been wanting to try the outputs option in Flycast, as well as MAME (Current) for a project I’ve been working on (it’s for lightgun force feedbacks controlled by the game).

However, I can’t even seem to get either core to open the necessary port 8000, as even when the option is enabled (in core settings for Flycast, in a system/mame/ini/mame.ini with the line output network), whenever I try to inspect the port on Linux:

nc -v localhost 8000

I get a localhost [127.0.0.1] 8000 (irdmi): Connection refused, implying that the outputs option hasn’t been enabled?

But when I try this with standalone MAME, using mame -output network and start a game like term2, I can connect to that port with the same above command and I do indeed see it flicking back and forth between output channels, as I’d expect it to.

Are these output options supposed to work on Linux? Do they require the user be in a specific group to work? Or is this a bug that’s better off on the RA issue tracker (and if so, is it a RetroArch frontend issue or the fault of the cores?)?

Using EndeavourOS, RetroArch installed from the extra repository.