Sophos Central encryption PIN length

Hello all,

is someone managed in setting a PIN lentgh of 4 digits, on Windows 10.

I have setup the right computer policy strategy:

Computer Configuration\Administrative Templates\Windows Components\BitLocker Drive Encryption\Operating System Drives

it is really applied as i see it in a gpresult

But when i want to reboot and encrypt with a 4 digits PIN, Sophos tell me 

PIN length is not correct.

Thanks for your help