See my post at Footswitch (BB) - #20 by persist
When I had a similar issue with the foot switch detector identifying my switches as latching, I immediately took my home built remote foot switch apart and tested all of the connections for good continuity and found no issues. Just to be sure there were no mechanical or connection issues, I tested this remote foot switch on my other products from Strymon, Pigtronix and Line 6; both switches worked just fine.
As annoying as Support’s reply might seem to be, this is pretty much the warranty standard for almost all products.
A possible workaround might be: if you were allowed to keep your original remote foot switch (if you didn’t have to return it to Singular Sound), you could try removing the left switch and swapping it out with the right switch in the replacement sent to you.
If you did have to send in the first one, and you’re handy with a soldering iron, you could buy a new switch (highly recommend Carling)—just make sure that it matches the MOMENTARY function of the remaining good switch (MOMENTARY “Off” or “On”).
Please let us know what you end up doing to resolve the issue.