Leaf Blowers

I have a Husquvarna 20" HU800AWD Mower. It has rear bagging, side discharge, and supposed to have mulching capabilities. I understand wet grass doesn't mulch but other than that this mower does not mulch at all and leaves a trail of grass when set up for mulching. I have tried mowing various lengths of grass, a different blade (both sharpened), various speeds, and cross mowing and I still get a line of mowed grass on my turf. I believe it is a design error, the grass builds up in the rear bag discharge area (door closed for mulching) and when full starts the grass trail, empty it,the mower mulches for 10 feet and the trail starts again! Has anyone else had this issue? Husquvarna says "no." If you have and found a solution, please share it with me>