My experience is that extra baking time will brown those stubborn crevices.
Also, try brushing egg wash on once at beginning of rise, let rise
UNCOVERED so egg wash dries out some, brush again just before putting into
oven. Be sure egg wash gets all the way down into the "joints" ... but
DON'T let it pool or puddle there (if too much gets down into the joints,
use your brush to flick it back up on top of the bread). (after you've
brushed on the second layer of glaze, you can sprinkle with sesame or poppy
seeds and they will stick on forever.) Be sure to rotate loaves
half-to-two-thirds through the baking time. And have courage -- let it
brown! You'll have a deep mahogany crust about 1/8" thick, beautiful
yellow bread inside, and a fine presentation. Enjoy!