Why does 5.6 fail to refresh project after creating a new C++ class?

Hello there!
I am using Unreal Engine 5.6 and Rider 2025.1.3.

Since I updated my project to 5.6, each time I create a new C++ class in the Editor, I get the following error in the IDE:

Failed to generate project model definition files for the project file
Failed to generate Unreal project model definition files. This could be due to a conflicting instance of UBT already running.

And I see my project tree with “Loading Failed”.

Most of the time clicking on “Try again” works. I was wondering if I am the only one having this problem. With 5.5 everything worked perfectly.

Thank you!

Stefano