Bastion Login Test failing continuosly

Bastion test is failing with host key verification

I have followed all the steps in the set up guide and validated the file path and permission of the key.

UserKnownHostsFile /dev/null
StrictHostKeyChecking no
ServerAliveInterval 120

Host bastion-?.fabric-testbed.net
User <Provided the bastion login available in user profile>
ForwardAgent yes
Hostname %h
IdentityFile ~/work/.ssh/bastion_key
IdentitiesOnly yes

Host * !bastion-?.fabric-testbed.net
ProxyJump <Provided the bastion login available in user profile>@bastion-1.fabric-testbed.net:22
##ProxyJump <Provided the bastion login available in user profile>@bastion-2.fabric-testbed.net:22