Problems after moving Windows11 to external drive

Hello,
I am new to Parallels as I have a new Apple Silicon Mac (MacBook M3 Pro) and I need to run some Applications on Windows.
Wanting to free up some space on my internal drive, I moved my Windows11 installation from my internal drive to an external SSD drive following this instruction. This worked fine for me at first.
After not using the installation for about a week, I wanted to use it again today. Unfortunately I got this message:

Hard disk 1 cannot be mounted
A file or device required for the operation of hard disk 1 does not exist or is being used by another process or you do not have the relevant access rights. The virtual machine continues to run, but the device is disconnected.

Original Message in German:

Festplatte 1 kann nicht eingebunden werden​

Eine für den Betrieb von Festplatte 1 erforderliche Datei oder ein benötigtes Gerät sind nicht vorhanden oder werden von einem anderen Prozess benutzt oder Sie besitzen nicht die betreffenden Zugriffsrechte. Die virtuelle Maschine wird weiterhin ausgeführt, das Gerät wird jedoch getrennt.
​

Also my Windows installation doesn't look normal (screenshot attached)

Is this a known issue? There are post on the internet with a similar problem, but some of them are already more than 15 years old and none of the solutions worked for me.
Is there a way to fix that?

Thanks for any help!
Franz

 

Did you ever get this resolved?

 

Unfortunately not.
I was lucky enough to find a backup of the VM on an external drive and was able to recover most of my data.