Not really the best picture, but this is the corner on the top of the shower curb.   Since the shower membrane starts out as a flat sheet, it needs to be cut to go over the curb.  This means that the inside corner is unprotected on the top.  I ordered a pair of these PVC liner inside corners from the Noble company to stick over these areas.  They were a bit tricky to install, getting fully into the corner, but they should protect this corner from water leaking in.