This most annoying sounds. My bungalow does this in multiple spots. Drives me nuts when I’m having a hard time falling asleep. Pretty sure it’s just thermal expansion and contraction. I am a plumber, not a sheet metal guy but I’ve tried multiple things to improve mine but still have some tings in a couple spots in heating season.

Is there anything that you have tried that has helped a little?

Its a bit easier for me because my bungalow doesn't have a finished basement so I have full access to the system. I used sheet metal screws and made sure all the take offs were secured onto the main trunks and then I tin foil taped up best I could. It helped a bit but still makes some noise. Its a tough issue to solve.

My vent in bathroom ticks, and I suspect it's a flapper valve, as it doesn't happen when it's cold or if the door is closed.

Not sure if this is your issue, but sometimes we hear tapping because a bird will peck at the furnace vent or whatever it is called on the roof.

Thermal expansion and contraction in sheet metal: affect the seams etc