Crash on creating a vector layer

Hi. I'm trying to use AEGP_CreateVectorLayerInComp during UserChangedParam. It creates the vector layer then crashes on windows & mac. The mac message it gives is: AfterFXLib`___lldb_unnamed_symbol1$$AfterFXLib:

I'm sure I'm doing everything right as just before I create the vector layer, I use AEGP_CreateNullInComp with no crashes. Both functions use the same parentCompH. I also tried using the oldest comp suite that supports this (v6) and the newest (v11), but both crashed.

Would really appreciate it if anyone could shed some light on this. Thanks.