MTS to set specific model files to post-layout views not working

Hi all,

I am trying to simulate a testbench wherein some cells are at schematic level, while others are post layout calibre views. 

Now because the PDK offers model files tailored for pre and post layout simulations (which I set in the corners setup) I need a way to differentiate which instances are extracted views and which are not in the case I have a mix of them.

Because in the corner setup I could not find any option to set a certain model files based on instance, I thought I could solve this by using MTS.

I went to the tree view tab, selected the instance I want to use a given model file:

set the desired model file for the instance, and applied the change

Now the issue is that when I try to run the simulation I receive the following errors:
"The instance `P0' is referencing an undefined model or subcircuit, `TRANSISTOR_pcell_0'. Either include the file containing the definition of `TRANSISTOR_pcell_0', or define `TRANSISTOR_pcell_0' before running the simulation".

Let's say the instances I was trying to set a specific model file is called myInstance, then such error happens for all the pcells which do not belong to myInstance or i_DUT (hierarchy is testbench.i_DUT.myInstance).

This makes me suspect two things:

1) the netlister is not reading model files for those cells whose MTS is not enabled (and which I'd expect to take the default model files as defined by the corners).

2) the instance affected by my MTS is not only myInstance as it was intended to be, but also its upper level i_DUT and all its content.

Are my hypothesis correct? And moreover, how can I get this to work as intended?

I have tried also to set the default models in "Global Model Files" in the first line, shown in the second picture, tell the simulator that all the other instances which are not myInstance should take the default models, however this did not change anything.

virtuoso version: ICADVM20.1

Thank you any help would be greatly appreciated!