Replaced lights & switches on 3 way switch circuit; not sure if I have wiring problem or product problem or both
Looking at your diagram, you are using the white wire as hot to the left-hand switch and black and red as travelers between the two 3-way switches. On the left-hand switch, you will find (excluding the green ground screw) one terminal looks different, probably a different color) than the other two. This is where the white wire goes. The black and red wires go to the other two terminals. Your diagram implies that this is wired wrong as you show the black wire going to the separate side of the switch.

Two more comments:
(1) I’m assuming that you also have ground wires running everywhere that you just haven’t shown. If not, stop and get a professional to help before you kill someone!
(2) You should add black tape to the ends of that white wire to show that it is not a neutral wire.