The orthodontic rubber bands can be bought in black, but they only work on the up/down tabs. The sliding tabs need to be glued shut. If you have no plans of switching the cars with the uncoupling tabs, this is an easy way to go because you'll never have to worry about it again.
If you want a working coupler, the only solution would be call Atlas. They're still being delivered to dealers so they may not have parts ready yet, but if you call in, I'm sure the issue would be taken care of.
