I have the same problem no matter how much I baby that section. I always assumed it was overprocessing (or relaxing in general), but even after being on LHCF for three years, low/no heat, protective styling, stretching relaxers, and texlaxing, it still breaks. I trim any splits in that area regularly and try not to manipulate that section. My crown is actually the reason why my hair is not BSL or longer.
My new growth in that section is very tightly curled when I let my hair airdry. I think it's 4B.
For a while, I thought it was my hood dryer...so I stopped doing rollersets. Didn't help - I actually think my hair tangled more in that section from airdrying.