Can you explain why NWM is still paying me while my claim is being reviewed? They said if they don't approve it, their accomodation payment is not owed back to them.

So I have jumped through all NWM hoops and still wasn’t getting answers. I have asked them myself to have their doctors and outside examiners review my file because it’s pretty self explanatory. My OB doctor has everything documented related to my uterine and bladder cystocele and rectocele. I have been a nurse for over 17 years so I have been able to explain to my claims agent that what she continues to ask me for is stated in the letter. My claim is still being reviewed since end January 2014 but here’s my question now. They sent me a letter stating they are still reviewing my claim but are providing me with financial assistance in the form of an accomadation payment while my case is being reviewed. They state therefore under a seperate cover, they issued me a payment and will pay me said amount monthly u till they finalize their determination. These accomadation payments will be applied toward my claim if my claim is approved. If they don’t approve my claim, the letter states this accomadation payment IS NOT owed back to NWM. The letter keeps saying that although northwestern mutual is providing assistance to me by way if a payment, they DO NOT accept liability for my claim. Now this is very confusing and puts up a big red flag! Should I cash the check? Can they be in default somehow? Something doesn’t seem right. I appreciate the check which covers the months thy haven’t covered but why such an explanation without approving my claim?