OWA “Manage Add-ins” Stuck Loading After Clicking Settings (Exchange 2019 CU15 / Exchange SE RTM)

The user is encountering an issue where clicking "Manage add-ins" in Outlook on the web fails to redirect on certain Exchange Server versions. The problem occurs specifically on Exchange Server 2019 CU15, Exchange Server SE RTM, and Exchange Server SE RTM Dec25SU. However, the functionality works as expected on Exchange Server 2019 CU14. Troubleshooting steps included moving arbitration mailboxes and migrating all servers to the latest version, but these did not resolve the problem. Isolating and testing each host individually didn't identify a server-specific cause. The user executed scripts to update CAS configurations, but that wasn't effective either. A workaround exists: manually opening the specified URL within the authenticated session allows access to the add-ins page. This issue appeared after CU14. The user suspects a bug introduced in CU15 or a later SU. The user seeks a solution or confirmation of the reported bug.