Sometimes the absorb remaining stays forever below what it says it should, sometimes it goes above, couldn't isolate the reason.
Here i have 10 more than the max, 1 minute before i had 3 less. I didn't change gear, level up, nothing i can think about.
Second issue : Retribution only reset the absorb value at the end of rest. So if after the fight you don't rest it doesn't go back up. I tried to rest once but had full resource and no cd so it wouldn't go back up. Having to use a cd outside fight just so it goes back up is annoying and could get you killed.