Can't select a Customer in Recurring Bill Plan

Summary

I created a Customer but I can't select it when creating a Recurring Bill Plan

Content

I created the Customer named “XX10IBM” and tried to create a Recurring Billing again but still cannot select it from the Bill-To Section.

I don’t see any issue with the Customer Account Details. The only thing i'm thinking could be the cause is because the Site Reference Accounts are blank. When I go back to edit the site and add reference accounts, the Business Unit dropdown isn’t showing any data.

Can you please let me know why I can’t select the customer when I create a recurring billing?