Hola Alejandro
This is normal behavior. The ProcessContainer process is not maskable. That is, the resulting image after applying the sequence of processes defined in a process container cannot be masked. However, each process instance inside a process container can have its own reference to a mask and its own mask inversion state, which always take precedence over the current mask of the target image. In other words, the current mask and mask inversion state of the target image are always ignored when a ProcessContainer instance is executed.
In your example, the MT instance has a reference to a mask image (Kleopatra_L) and no mask inversion. Hence, it is executed this way, irrespective of the current mask and mask inversion state of the image. Note that the MT instance would be masked directly with Kleopatra_L, even if the target image has no mask defined.
Although I recognize this behavior can be counterintuitive sometimes, this is the way ProcessContainer works, and it has to work precisely in this way because otherwise we couldn't encapsulate a sequence of processes as a self-sufficient object (e.g., an image's processing history). Always remember that processes and images are completely independent each other in PixInsight; this is just a consequence of that isolation.
