The stubborn freehub that ate my whole afternoon in Austin

Had a 2018 Trek with a creaking bottom bracket that drove me insane for three full shop hours one Tuesday. Customer insisted it was the crank, I swapped it, still creaked. Turns out the frame's threaded insert had worked itself loose inside the carbon shell. Not the BB, not the crank, not the chainring bolts, the actual bore in the frame. I had to pull the motor out on a mid-drive e-bike to even see it, which took forever because of the wiring routing through the downtube. By the time I found it I had already charged the customer for a new crank install and had to eat the labor on the refund. Anyone else dealt with a press-fit shell that started spinning in the frame? How did you secure it without a full carbon repair?