Sauf que plus indicative is synonymous with a moins que + subjunctive, but was marked incorrect in quiz. Suggest that lesson mentions this alternative

This is a bit beyond my level but I did some reading.

Sauf que is very complex and can be followed by indicative/conditional. But it  is not really synonymous with à moins que + subjunctive.

Sauf si + indicative is synonymous with à moins que + subjunctive.... based on my reading