Basicly was applying full iluminate healing shield on my self and had a mob attack me it dosent reconunt the healing shield unless the shield expiers or its fully absorbed if i keep applying the shield it will never recount anything..
It does record it a little strangely. The reality is in a raid the shields aren't going to go unbroken / unexpired so the overall data should be accurate. WoL sometimes places me slightly higher than recount which perhaps accounts for those unused / unexpired shields right at the end of a boss encounter.