After using Form for custom identity authentication in PowerBi Report Server, the custom visual styl

Hi,Twinsin . I am glad to help you.

According to your description, you are experiencing an issue where a custom visual object in a report is not displaying properly in Power BI Report Server Web Portal.
The error number is 401, which generally means ‘Unauthorised’, i.e. the client requested a resource that requires authentication but failed to provide valid credentials!

I hope my suggestions below can help you.
1. Check that the credentials for the custom visual object on the Report Server Web Portal are set correctly and that they are consistent with those in Desktop.

2. Cross-domain requests: If your custom visual object needs to load resources from a different domain, you may need to configure a Cross Domain Resource Sharing (CORS) policy to allow these requests.

3. Authentication tokens: Custom visual objects may need to use authentication tokens to access protected resources. In this case, you need to ensure that the tokens are passed correctly in the request and that the server is able to authenticate these tokens. You also need to ensure that the authentication tokens have not expired.

I hope that the related documentation and issue below will help you:

URL:
Troubleshoot custom visuals in Power BI Desktop for Power BI Report Server - Power BI | Microsoft Learn
Re: Power Bi Report Server: Custom Text Filter vis... - Microsoft Fabric Community
Power BI Report Server - Custom Visual 401 Unauthorized · Issue #172 · microsoft/Reporting-Services
 

For authorisation validation issues with custom visual objects, it is recommended that a member of the team with programming skills be contacted to resolve the issue. This may involve writing relevant authorisation scripts to ensure correct authentication and authorisation.

I hope my suggestions give you good ideas, if you have any more questions, please clarify in a follow-up reply.
Best Regards,
Carson Jian,
If this post helps, then please consider Accept it as the solution to help the other members find it more quickly.