Help - Calamares does not format the root partition, stalls during installation

I installed KDE Linux on an external NVME connected to my Lenovo x390 GEN1 notebook via USB-C. This runs smoothly.
When I tried to install KDE Linux on the internal NVME of my notebook, Calamares crashed while formatting the hard drive.
The installer should erase the entire hard drive and create the partitions itself.
I started the notebook with GParted and could see that Calamares correctly created the 4GB EFI partition, FAT32, but the root partition was not created, the memory was not formatted.
I tried three RAW versions from days 20251025, 20251024 and 20251023.
I didn’t find any information on the internet that Calamares might have problems formatting NVME drives larger than 500GB with btrfs. With KDE Neon on my computer I don’t have this problem. But root is on an EXT4 partition.

Is this a problem with my computer, Calamares or KDE Linux?