grub-probe does not show right abstraction (at NVMe)

[Dieter Faulbaum]

grub-probe -t abstraction /usr
show only:
lvm
and not something like this:
cryptodisk
luks
...
lvm

the OS is: Debian testing, the version of grub-probe is: (GRUB) 
2.06-7

the relevant part of the filesystem looks like this (with lsbkl):
nvme0n1                                       259:0    0 953.9G  0 
disk  
├─nvme0n1p1                                   259:1    0   487M  0 
part  /boot/efi
├─nvme0n1p2                                   259:2    0   954M  0 
part  /boot
└─nvme0n1p3                                   259:3    0 952.5G  0 
part  
 └─nvme0n1p3_crypt                           254:9    0 952.4G  0 
 crypt 
   ├─vg0-usr                                 254:10   0  39.8G  0 
   lvm   /usr

calling 'grub-probe -t abstraction /usr' with a SSD works fine:
cryptodisk
luks
gcry_rijndael
gcry_rijndael
gcry_sha256
lvm

layout at that computer:
sda                 8:0    0 476.9G  0 disk  
├─sda1              8:1    0   512M  0 part  /boot/efi
├─sda2              8:2    0   244M  0 part  /boot
└─sda3              8:3    0 476.2G  0 part  
 └─sda3_crypt    253:0    0 476.2G  0 crypt 
   ├─vg0-usr     253:2    0  23.6G  0 lvm   /usr