Your root issue seems like what Fred said also. I usually just cover them up with soil but if the main fans are already well covered then you will be possibly putting them too deep. Depending on what type soil you have or if you add admendments they will decompose with time and settle down and be more compacted, this could cause the roots to be exposed as well
A lot of times I will have 4 or 5 smaller fans growing in the middle and their roots growing up and over the bigger roots (I suppose trying to get to the soil) and if I don't divide them those fans sometimes will suffer and stay small, if I cover them then the rest of the plant is too deep. I just wait until the end of our season and divide and replant them.
