Why Did Partner Switch Suits?!?

This defensive problem came from "Dormer on Deduction" by Albert Dormer
/ bridgevid

[@YCLP]

At the table, I would probably think partner likely made a mistake. In this problem setting, I got the answer right.

[@ahmetgrcn2663]

Thanks Pete nice problem

[@sharonguy3726]

i would realy hope for a heart shift either from what patner had or from Axxx of heart. so i wouldnt be surprise by the shift