Why am I unable to select the business unit as my configuration owner in determine tax applicability

Summary:

I am setting up tax for a new business unit. I am unable to select the business unit as the configuration owner in the determine tax applicability rule. Legal entity is the only one that will show up for me to select.

Content (required):

business unit in tax determining factors

Version (include the version you are using, if applicable):

Oracle fusion

Code Snippet (add any code snippets that support your topic, if applicable):