Hi Nando Jung,
Welcome to the Microsoft Q&A Platform. Thank you for submitting your query here.
The issue occurs when one of your client users logs into the WVD environment and the screen turns black.
If you are a Windows user, please ensure you are using the latest Generally Available (GA) client version available at: Remote Desktop client for Windows.
Please refer to this Azure Virtual Desktop sign-in screen is blank.
Please indicate:
- Did you use a marketplace image or a custom image?
- Are FSLogix profiles or local profiles being utilized?
If this resolves your query, please consider accepting this response as the answer, as a token of appreciation.