I had the same problem with my prewar 1668 front trucks and one of my postwar cabooses.  I have 10 1122E switches on my layout.   There were 2 switches that the 1668 and caboose would derail intermittently as they were going over the bump metal “X”.   I removed the metal “X” and they would still derail going over the bump.  I took a SMALL ROUND file and filed out the plastic bump in both the straight side and curved side of the switch so there was no bump.  It worked no more derailing.