You might want to consider rewiring.
Remove all the wires from both switches.
Use a voltage sensing wand Like this to determine which one is the hot wire. Based on your pictures and comments, I suspect red is hot. Red is commonly line when the gang box has a 220 (red/black/white) romex cable. Black and Red are both 110 Line, with White S neutral. If you wire the red and black, you get 220V and white to either you get 110V.
If this is the case, wire the dimmer in the box with the red wire so to Line (red), Neutral (white) and ground. Also on this same dimmer, wire the wire that goes to your other switch as, black to Line and White to Neutral. This dimmer will be a remote dimmer.
On the other switch, wire both white wire to Neutral (on goes to load and other comes from the first dimmer.
Now wire the black wire from the other dimmer to Line, and the black wire from the load to Load, and of course wire ground. This is the master dimmer.
What you have now is a master and remote. The remote does. It control a load. You can now pair both dimmers to you hub, the. Use the z-wave association tool to link the slave to the master. This will cause the slave to talk directly to the master via a-wave instead of using the traveller. Even if the hub goes offline, these dimmers will talk to each other, but only as long as they are paired to each other.