Important information about this issue

This issue affects customers with a new installation of the Address Validation for Dynamics 365/Power Apps on version 2.5.0.15 or higher.
If you upgraded from a previous version to 2.5.0.15, you are not impacted by this issue.
A workaround has been identified and is documented in this article.
We are working with Microsoft on a permanent resolution that will be introduced in version 2.5.0.16 and higher. We thank you for your patience.

Issue Description

If you are setting up your Address Validation for Dynamics 365/Power Apps, you will encounter an error if you click the Validate API Key button (see step 4 from the configuration article).

Status

Root caused identified:

A background process required to perform API validation has been turned off and must be turned back on.

Current Status:

Resolved.

Workaround

Manually activate the deactivated process

Navigate to the Power Apps Maker Portal and select the environment where the Address Validation for Dataverse is installed.
Click on "Solutions" and open the "Address Validation for Dataverse" solution

Filter the components and look for "Process" only
Look for the process named "Configuration - Validate API Key"
Click the "... " sign and click "Turn on"

Verify that the process is now turned on.

Note that this issue has been permanently fixed in the current release.