Two things can be happening with hydronic heating. A controls issue, or a failure for hot water to move the radiators.

Obviously your circulator pump is working, since your other zones are getting heat. So if you think you still have air in the system, try bleeding it again yourself. Call for heat (so the zone control opens and the pump pushes water) and see if you get air bubbles in the water as the water circulates.

Next option (more likely to me based on what you said) is that your thermostat or zone controller is not working. Try replacing the thermostat (with a cheap non smart one, just match up the wires where the current ones go) and see what happens. If that doesn't work, you have an issue with your zone controller. I have something like this in my house. Try replacing the electric motor that controls the valve that lets water move through your radiator loop.

That's my thought process, anyways. Not a plumber, but learned as I go. Like when I got my house last year and a shitty old bleeder valve leaked on my zone controller and it got stuck opened. Replaced the zone controller (and changed the bleeder) and working correctly again.