Hmm… Okay, so master in the first spot (left most switch) works for turning on and off all lights, right?
We’ve got the red wire going from the traveler spot on the master switch thru to the traveler spot on the first aux switch AND you have neutral connected to the neutral spot on the first aux switch., right?
But the aux switch isn’t working.
Here’s what I’d do next to test it… take the master out of the wall. Leave it wired up properly, but have it accessible. Next, grab one of your aux switches and wire it directly to the master: traveler to traveler. Obviously have to hook up neutral here too. Obviously be careful here when you turn power back on as you’ve got exposed wiring here, but try the aux switch this way, see if it works.
If so, then there’s a problem with the wiring somewhere. If not, then we’re sure the aux switch is the problem. Do the same with the second aux switch.