Even after following your advice, the issue wasn't completely resolved. It's not so much that the grass is missing, but rather that the lod for the entire area surrounding Whiterun is problematic.
The affected area seems to correspond to the scope of modifications made by the 'Whiterun Has Walls reborn' mod. It appears there's a significant conflict between DynDOLOD and 'Whiterun Has Walls reborn'.
However, this is just a minor visual issue when looking out from inside Whiterun. The main, game-breaking problem has been solved. Thank you for your help!