A family of Microsoft spreadsheet software with tools for analyzing, charting, and communicating data
Here are some possible reasons:
Service start issue: Even though you said SSMS can connect to the URL, it may be that the SSAS service is not running on the remote server or is not properly configured. You can try restarting the "SQL Server Analysis Services" service on the server to address this issue. In the service manager, find the "SQL Server Analysis Services" service, right-click and select "Restart".
Compatibility issue: Make sure your Excel version is compatible with the Analysis Services version. If there is version compatibility issues, a connection may not be established.
If none of the above suggestions solve your problem, I‘d’ suggest you raise a support ticket to Microsoft.
Please contact your admin/IT department create a support ticket via Microsoft 365 Admin Center> Support> New service request. That support team there will have the correct channel and resources to help you investigate more and find what exactly the reason has caused this situation.