OTP not accepted

I have set up the Vault server (v.172), created a policy, a user, a role, everything works fine. I have set up vault-ssh-helper on remote host, it works fine. Still, when I generate the otp for the user using the vault client and try to ssh into the remote host, I get this:
ssh linux-user@x.c.v.b

And it just hangs.

On the remote host, in the vault-ssh-helper log file I can see this:
2021/07/08 12:00:38 [INFO] using SSH mount point: ssh
2021/07/08 12:00:38 [INFO] using namespace: my_namespace
2021/07/08 12:00:38 [INFO] linux-user@x.c.v.b authenticated!

What can be the problem? Can I see more logs somewhere?