Hmmm - if you have shot this stuff before, I don't want to insult you

, but yeah it sounds like extreme over exposure.
Pola stuff can be tricky. I have had two problems with it:
Shooting pinholes and being WAY off in my exposure and then getting confused between over and under exposure, but too, I have recently had problems with my holder. I tell you this hoping to maybe jar your investigative ideas. My holder won't latch the film sometimes and then I pull the film and sleeve up together and NADA! But then it comes out tar-black. Light leaks, bad film perhaps (not likely)
Good luck - I get expired Pola stuff from a local cam store (it's all I can afford), so I don't get it at the over-inflated-new-box cost. That mess is too expensive to have anything go wrong!