I don’t know what instrumentation those aircraft had, but every one I flew had dual compasses for the very reason that the do occasionally but rarely fail.
So a question: What was the weather?
Had these pilots completed their instrument training or were they still in training?
Five compasses failing simultaneously on five different aircraft is not only impossible but the concept is ridiculous.
Remember, the magnetic compass has been used on ships as far back as the year 1400.
The weather was fine, but, deteriorated. The problem was that Taylor was not a good navigator and blamed the compasses for his failings.