The Sign account for name@... is associated with a different profile

We currently send a document to Adobe Sign for signing using the Adobe Sign API. This user has two accounts with Adobe, personal and company.

The user can select which account they want to use after logging in.

The personal account has the privelages to sign documents. However, when selecting the personal account they get the error:

"The Sign account for name@... is associated with a different profile. Switch to your (company name) profile."

The user doesn't have an issue sending documents for signing using Adobe Acrobat and their personal account.

What is the issue with their personal account?