Possibly wrong size luff tape?
Unless you are using the same exact jib with the same exact furler that you employed before without any problems, then I suspect that possibly the luff tape is a size 6 you are placing into a furler for a size 5 luff tape.I beleive the standard luff tape size is size 6 for most furling jibs. This size is used on all but just about the largest of boats.However, some small furlers, the smallest Harken for example, require a number five luff tape which is a bit smaller than the standard number 6.Hence, it is possible your problem lies with the luff tape on your furler.Try the sail in a different furler, one specifically designed for a number six luff tape and see how well it goes in that furler compared to yours.