Why is my beef broth the wrong color?
As suggested by OP in a comment, it is likely that a milky, creamy broth is the result of fat emulsifying into the broth due to too-violently boiling the broth. For context: when making a Tonkotsu ramen broth, this style of milky broth (typically made with pork rather than beef bones) is often the desired result, hence you'll find recipes calling for a sustained rolling boil for hours (whereas traditional French stocks would be kept at a simmer), or even suggestions to blend up your broth.

Thus, the answer to this question would be to cook the broth at a simmer, rather than a rolling boil.