Depending on what cx_Freeze is doing with packages, I wnder if this What's New 3.4 porting note is relevant:

  * Frozen packages no longer set ``__path__`` to a list containing the package
  name, they now set it to an empty list.  The previous behavior could cause
  the import system to do the wrong thing on submodule imports if there was
  also a directory with the same name as the frozen package.  The correct way
  to determine if a module is a package or not is to use``hasattr(module,
  '__path__')`` (:issue:`18065`).