If you have another back try that and see if the same happens. If it does happen the problem is probably with the camera; if it doesn't happen the problem is probably with the back. I have used Bronicas for many years and I never experience anything like this so can't help further. The cameras and backs are usually pretty robust and seldom give fault. Hopefully someone here will have an idea of what is going on and will be able to help.
The aim of art is to represent not the outward appearance of things, but their inward significance.