Thanks for reaching out . When you switched to Role-Based Access Control (RBAC) for your Azure Functions app, it's possible that the permissions assigned to your user account, or the roles associated with the function app may not have sufficient write access. Some features of Azure Functions require write permissions to function correctly.
If you are assigned the Reader role, for example, you won't be able to view or modify functions within the app, which could lead to the issues you're experiencing. To resolve this, you should ensure that you are assigned an Azure built-in role with write permissions for the function app or the resource group it belongs to.
ref:
https://learn.microsoft.com/en-us/azure/role-based-access-control/troubleshooting?tabs=bicep#symptom---some-function-app-features-are-disabled