Yes Pablo, but more specific, the sun mesh drives one flank and the ring drives on the other side, whereas in a single mesh you only have loading typically on one side of a tooth. On top of that, as a tooth is loaded it causes the root behind it to load in tension. When the next tooth is loaded the same root location is reversed into compression. When this same root is exposed to mesh on the ring gear, the opposite occurs. The first stress is compression, then tension. Some argue that this t-c-c-t is really a unique application of the goodman correction, and could be treated like a single cycle. Further complicating is that the exact root location of peak stress for each mesh may not and probably is not, the same, nor is the t and c magnitude the same, depending on deflection and other factors....
.. but this digresses. The fatigue in this case is starting at the bearing race ID, so more like a rolling wheel fatigue than gear tooth problem I would venture to guess.
AH may not really understand this, since they don't design the transmission we are told. Likewise, the transmission design team may not understand actual flight loads, since they are not the air vehicle experts. I have said before, parts only break when load exceeds strength. Which path to go here? My guess is load is not fully understood, but there may be a strength differential between suppliers.