Based on doing a code review and talking to Jordi I think we need to make the following changes to the code to make market based work as intended

In assessments/models.py

def market_based(self):
        return self.question.market_based and self.uses_mbi

to

def market_based(self):
        return self.question.market_based

We have seperate method called uses_mbi and its what it should be used for market_based is based solely on wether the parent question is market based

The market based Logic is completely wrong it should be

@memoize_property
    def calculate_market_based_emissions(self):
        """
        Calculate the specific market based emissions for this answer.

        Uses the regular emissions and supplants in the custom factors
        entered for the answer.
        """
        if not self.market_based:
            return []

        gwp_group_id = getattr(self, 'gwp_group', None)
        if gwp_group_id is None:
            gwp_group_id = self.company_unit.company.gwp_group_id

        if self.market_based_instrument:
            # Use the mbi's factors
            custom_factors = self.market_based_instrument.get_factors()
        else:
            # Use the activitie's residual factors
            custom_factors = get_potentials(
                self.activity.residual_factors.all()
                    .select_related('gas', 'unit'),
                location_hierarchy=self.location.get_location_hierarchy(),
                daterange=self.duration
            )

        if not custom_factors:
            # Cannot find residual factors matching the answer, so return
            # a copy of location based emissions, so we can set the
            # is_market_based flag on
            emissions = [
                Emission(
                    e.gas, e.amount, gwp=e.gwp, path=e.path, answer=self,
                    aggregate=e.aggregate, multiple_paths=e.multiple_paths
                ) for e in self.emissions
            ]
        else:
            emissions = emissions_from_graph_with_override_factors(
                activity=self.activity,
                location=self.location,
                daterange=self.duration,
                value=self.value,
                unit=self.unit,
                gwp_group=gwp_group_id,
                factors=custom_factors,
                answer=self
            )

        for em in emissions:
            em.is_market_based = True

        return emissions