Macbook M4 - Windows 11 24H2 - Freezing after Standby? - Only on External Monitor

Hello,
i have following issue. If I run VM (Win11 24H2) and I leave the Laptop for maybe 30-60 min, the VM freezes. First I thought something bigger is wrong, but it only happens then the Macbook is running on an external monitor (Laptop is closed). If I use the Laptop normally without the external monitor, everything works fine.
If the VM freezes, I have the option to switch to coherence mode and switch back, or close/open the Laptop. It is not a big deal, but not comfortable. Anybody has the same issue or has a solution for this strange behavior. I am quit sure that it has something to do with the visualization of the VM and not that Windows is freezing. It seems like the picture of the VM is somehow freezed and needs some trigger to come back.

Thank you