I have no idea, but the exact same thing happened to me when I was hired by Nuance.
I was hired and signed the contract, I purchased some new hardware, Nuance IT installed everything on my computer and then I waited and waited for nearly 3 months before I actually started working. I really wondered if it was all just some kind of scam but eventually I got the go ahead and I am still working for them now, a few years later. I was only in training for a few days and I have basically just been stumbling along ever since. It has been a real struggle for me, to be honest, but I am lucky that my team lead is super nice. I know Nuance's problems are not her fault. Nuance is a just a really weird company, that's the truth. It ain't good.