I'm not aware of any sort of casing affecting the reading of function instances @Matteos . If you're able to create the function instance from within Visual Studio, it's definitely odd that you can't view it.
What I suggest is running Fiddler, observe the network traffic from you devenv instance when you're on that screen. I doubt it's a permission issue because you're able to create the function app and view it in the portal. This will hopefully reveal the API call that's failing or returning an empty result. Other than that, it would be best to run the Report a problem option from the Feedback tool.