LLC

Hello, My name is David and was advised to post this on the legal forum; I have 4 single family rental properties in Florida. I was advised to set up an LLC for personal liability protection for those properties. They are all conventional loans. I have contacted 3 of the 4 Mortgage companies that hold my notes and each of their assumption departments told me that their investor guidelines prohibit that transfer as I was approved for the loan not my LLC. What should I do? Any good resource books or web sites? All advice welcome. Thank You! David