Rope is one potential cause of bread and bun spoilage. Over a year, if you have the microorganisms in your bakery, they are accumulating. You should do a deep clean of your whole bakery section. Bake and then see if you have an increase in shelf life of an extra day. Then should ask your premix supplier if they have incorporated products like Calcium propionoate, acetate to delay the rope onset. Also make sure your premix is dosed optimally. Check, which preservatives are allowed in your country.Sorbic acid was allowed in Europe for this application, in South Africa only this year. Between these three, your product shelf life in combination with good cleaning procedures of Baking pans, mixers, tables. Also allowing bread to cool adequate will also help, before packing, as condensation is also an assister.This problem would be greater in summer months>30 degrees. Winter less, unless front selling section is climate controlled.