I Had the Problem, Too!
We had the same problem with our 450 with in-mast furling, B&R rig and no backstay. There was that bend in our mast that you described and when pulling out the main, the second layer of sail tried to come out with the first. We had our rig retuned, removing most of the bend and that solved the problem. With a Passage 420 and inmast furling, you are a cruising boat, not a racing boat. Forget about mast bend, straighten the mast and you will enjoy the boat more. By the way, have an expert that really understands the B&R tune the boat because tightening on the forestay will not solve the problem.