To replicate, create a custom entity, and add either a bow or sword to its gear loot table (similar to a zombie or skeleton). Set the probability to be enchanted at 0%. When the entity spawns (naturally or using a spawn egg), the weapon has no texture rendered (the weapon looks all white).

The weapon is only rendered correctly when it is enchanted. To replicate, set the enchantment probability to 100%. Go into game and spawn in the entity, or find the naturally spawned entity, and the enchanted weapon will be correctly rendered.

Expected behavior: the non-enchanted weapon should have a texture.

Additional notes: non-enchanted and enchanted armor always renders correctly. This issue appears to be with only non-enchanted weapons.