802.1x fallback

Hi there

Im trying to configure 802.1x on the Sophos 48port Switch

For Port 3, I have set PVID to VLAN 120 and also Untagged on VLAN 120 for Port 3.

But for computers which Fail to connect 802.1x , I want them to fallback to VLAN 140 which is Guest network.

I have configured my switch with the below settings however computers do not get pushed to VLAN 140 if they fail 802.1x

Any ideas how to make this work?