Summary
Getting an Access Denied error when using the Check Credential for a specific Credential in the Data Flow Probe Setup>Domains and Probes>Domain Name>Credential
Question
Even though the credentials are correct you are getting Access Denied when using the Check Credential feature in the UI.
Answer
This might be resolved by reimporting the credentials following the advice on this link but exporting and importing to the same server using the JMX console commands.
exportCredentialsAndRangesInformation and importCredentialsAndRangesInformation
Please find more details here: https://docs.microfocus.com/UCMDB/11.0/ucmdb-docs/docs/eng/doc_lib/Content/Jmx_reference/Hardening/JMX_ExportImportEncrypted.htm