I use both FL-820S & FL500S filters and can share your frustration. In my experience, the problem is ill-fitting filter wrenches, likely junk items from indifferent manufacturers with sloppy tolerances. If the wrench, when fit onto the can, can be even slightly rotated by hand, it's going to be troublesome...especially in locations that are difficult to service.
My solution was to carry a filter with me as I shopped for proper fitting wrenches. Eventually, I found wrenches that fit snugly, i.e. they actually kind of snap on and off. In my area, there is a wide variety of wrench choices...some are poor, others are great. If you can find a wrench with mini flutes, the fit will be much better. Keep looking.