unable to add SD-20 RED to Sophos XG 18.3

Hi,

I am trying to to add SD-20 RED to Sophos XG 106 V18.0.3 (MR3)

I am entering all needed data and press "SAVE". Then the little wheel start to turn and turn and turn... and never comes back.

No error. No nothing.

Admin log says: RED device 'R20XXXXXXXXX' was added by 'admin' from '192.168.1.101' using 'GUI'

But that's simply not true. The RED never appears.

Ideas??