ATF test fails with "reference is NOT valid" error when attempting to set a reference field's value

All Supported Releases

If you are able to select the referenced item on the test step, yet the reference is invalid during the test, this is often due to domain separation. If the test impersonates a user that cannot access the referenced item from its domain, the reference will be invalid.

Ensure that the impersonated user on the ATF test will have access to all referenced records and items. Just because you are able to select the record when configuring the test, especially if doing so from the global domain, this does not mean the impersonated user will be able to access the same record.