GFI Question

In a house today the GFI in the master en suite bathroom would not trip, either with my tester or the trip button.
In the other bathrooms the outlet would trip with my tester and I would have to go and reset the GFI in the master en suite bathroom.
Is it more likely that the GFI was wired incorrectly or that it was defective?

Either one is possible, but I’d put money on defective. The present generation of GFCI’s will not energize at all if they’re miswired (“safe lock”), but former models of GFCI could. Good catch.