After the infusion, was there any change in the power level of the item? At light level 303, there must have been a +5 mod on the item. This mod item does not count when infusing, only the base level. So your end result should have been, at minimum, a 298 item. I am not sure where you are with the game, but the mod thing kind of confused me at first. This is the only reason I know that might cause this type of issue. Best of luck on getting it resolved.