Heads up on using POA in bank. Unanticipated problem.

Using POA at bank just might cancel your beneficiary status! I was financial and heath POA for my mother and the only heir. For 19 years I managed her finances and everything else. We had everything set up correctly. My mother had a few CDs and a moderate savings account. I was listed as beneficiary of POD on all these. I used a checking account with both our names for her expenses. In the year before she died I transferred a CD to her savings to ensure adequate resources for her bills. I also set up a recurring transfer from the savings account to the checking in the amount of her largest two expenses. This was a mistake. I had to use the POA to set this up. Unbeknownst to me, the bank then removed my status as beneficiary on this savings account. Now this absolutely did not have to happen nor did they tell me at the time. Simple paperwork could have retained both but I was not informed. So when my mother died I had to go through the expense and hassle of probate when we had arranged matters so I wouldn't. The amount in the account was just over the limit for a simple form to allow me to claim the account. I am so annoyed and wanted to let others know of this possibility.