V12 Mobile disable field not working for lookup fields

We have some mobile applications developed with class and representations that in version 11 we used the function:

 [L]ASTATUS = fmet this.ASETATTRIBUTE("YCPLWST","$isDisabled","true")

And all the fields become disabled in version 11 in mobile or desktop versions.

Now in version 12 the lookup fields stay enabled only, only text, date and other fields are disabled, is this a bug or a new behavior?

If we use the representation in desktop the behaviour is ok in version 12, all the fields are disabled, but if we use this representation in mobile environment, only text, date and other fields are disabled, lookup ones still enable.

Thanks.