Please try setting Settings | Build, Execution, Deployment | NuGet | Credential Provider to NuGet/.NET CLI plugins.

If that doesn't help, please create a new support ticket (Help | Contact Support) with the following logs:

• Enable NuGet All, NuGetSearch trace scenarios via Help | Diagnostic Tools | Choose Trace Scenarios;
• Reproduce the issue;
• Share the output in the NuGet tool window | Log tab;
• Collect logs via Help | Collect Logs and Diagnostic Data;
• Disable the trace scenarios enabled previosly;