Unable to mount bde1

[BertV1]

When i use bdeinfo -k <fvek-key> /vol/path I can see the bitlocker encrypted volume, more specifically a USB encrypted with bitlocker, is not locked anymore. Without the FVEK key it would tell me it is locked:

deinfo /dev/sdb1
bdeinfo 20240502

Volume is locked and a password is needed to unlock it.

Password: 

Unable to unlock volume.

BitLocker Drive Encryption information:
	Volume identifier		: 
	Encryption method		: AES-CBC 128-bit
	Creation time			: Sep 13, 2024 13:29:08.656687200 UTC
	Description			: 
	Number of key protectors	: 2
	**Is locked**

Key protector 0:
	Identifier		: 
	Type			: Password

Key protector 1:
	Identifier		: 
	Type			: Recovery password

notice how is locked is not there anymore:

bdeinfo -k <fvek-key> /dev/sdb1
bdeinfo 20240502

BitLocker Drive Encryption information:
	Volume identifier		: 
	Size				: 3.9 GiB (4215243264 bytes)
	Encryption method		: AES-CBC 128-bit
	Creation time			: Sep 13, 2024 13:29:08.656687200 UTC
	Description			: 
	Number of key protectors	: 2

Key protector 0:
	Identifier		: 
	Type			: Password

Key protector 1:
	Identifier		: 
	Type			: Recovery password

I can also get to the point where i have a /mnt//bde1 file using the same FVEK key.
My issue is i cannot properly mount this file:

mount -o loop,ro /mnt/fuse/bde1 /mnt/file_system
mount: /mnt/file_system: wrong fs type, bad option, bad superblock on /dev/loop0, missing codepage or helper program, or other error.

I've tried various alternatives (vfat, exfat,ntfs-3g) but none seem to work.
I'm wondering if i did something wrong or my confidence in the supposed unlock of the drive is missplaced ?

Thanks