Thank God the horrible NDB is now effectively a thing of the past. I spent the early years of my flying career driving a Piper Navajo around the rocks of the Pacific Northwest of North America. I had a near identical experience of a false passage indication with a probable CFIT accident if I had not listened to my spidy senses.
NDB’s did result in some innovative procedures though. One airport (CYCD) used to have a NDB approach with a big bend at beacon (FAF). Waiting for station passage put you well West of the remaining portion of the final track towards high ground and required you very quickly intercept the final approach track outbound. However it was often calm in the morning and before you reached the NDB you passed over a pre pollution control pulp and paper plant. The trick was a soon as you smelled the plant you put in 3 degrees of left bank which would mean you would be almost perfectly aligned with the runway at beacon passage