It COULD be the ammo; I've seen bad batches from several manufacturers. Although WWB is less expensive ammo, if it has worked in the past, then it should work now, too.
Any changes since the last "good" range visit? New grips, new barrel or other internal parts, a laser or flashlight?
Is it possible that your gun is clean, but not lubricated? I've seen similar problems from guns that lacked lube, as the extra friction can prevent the slide from moving quick/far enough to extract/eject the empty casing.
Other possible causes could be improper assembly (recoil spring/guide?), a broken part in the weapon, or a serious burr that is interfering with slide travel.
Hope this is helpful. Let us know what happens.