I am building a new layout using traditional Lionel tinplate track and so I plan to use a number of the Ross Plate tubular rail switches. I am glad I read this thread because the first ross plate switch I installed and tested had the same issue noted by the OP. Turns out it was the same problem, there was a screw touching both anti derail track pieces. This is a simple fix for the ross plate switches when you find the problem- remove the offending screw. Top picture shows the screw removed and the bottom one shows the screw in place.