We asked clarification to SODE developer, and the issue is caused by a new optimization that has been added to SODE 1.6.4 that, in order to speed up loading, will ignore FSDT folders that are not jetways, and it use the "FSDT_Jetway" and "FSDT_SODE_*" patterns. Since KCLT jetways are in a folder named "FSDT_KCLT_Jetway", they don't match those patterns, so SODE is ignoring them.
The solution is to rename this folder:
Addon Manager\Simobjects\Misc\FSDT_KCLT_Jetway
to be like this:
Addon Manager\Simobjects\Misc\FSDT_SODE_Jetway_KCLT
so it will match one of the patterns and won't be discarded by SODE.