A beneficiary you've added to the estate may also be an executor (acting or otherwise), or vice versa.
Rather than having to enter their details to either section, you can click on the three-dot menu next to their name, and click "Make Beneficiary/Executor" (depending on the section you're in).
The contact's information will then be duplicated to the opposite record type.
If you are still having difficulties, please create a support ticket by emailing firstname.lastname@example.org, or wait for a response if you've already created one.
If you've created a support ticket but solved your issue using this article, please let us know by responding to the follow-up email.