I see what the issue is, when we are calling z_top() it is not referencing the "other" object correctly and is checking against itself. I will modify the code so this cannot happen. It is weird that it is not occuring in the example project -- so it must be a bug caused by instance creation order. [UPDATE: I uploaded new versions of the source code that should resolve the issue -- I was able to import only the scripts from the YYMPS to replace the old ones and was able to validate it works]