Remote Desktop Gateway not Working

Hi Devolutions,

We've posted about this before but have never had it resolved.

We are currently using RDM v14.1.3.0 64-bit.
We have a certificate installed that is supposed to allow our gateways to properly authenticate.
My laptop is a Surface Book, which is Azure AD connected. Likewise are my colleagues', save one who is using IBM Lenovo ThinkPad Carbon X1.
None of the Surfaces can properly connect to the gateway, but the ThinkPad can. All machines are domain-joined.
We have also tested with non-Surface machines that are not domain joined - we have a DELL test unit in the office which doesn't have this issue.

My colleagues and I share this account to access each of our clients' servers without worrying about separate logins.
By using the same account, we have the same access, same stored credentials etc.

For the purposes of this post, I am logging into my laptop (Surface Book) at the start of the day. I've logged into my laptop as User A. User A is local admin.
We have a remote desktop gateway to establishes a connection to client servers.
Whenever I attempt to connect to a clients' server, or the gateway itself, I am greeted with an authentication error (see "rdg1" (when connecting directly to the gateway) and "rdg2" (when connecting to a client's server)).
I can enter the connections' properties and turn off the gateway and have it work, but we don't want to do that for security reasons (see "rdg3").

The bizarre thing is that when I log in as User B on the laptop, who isn't a local admin, sign out, then log back in as User A, the gateway works and can establish a connection. Logging in first as User B also allows the gateway to work. For extended testing, we added a User C into the mix, yielding the same results as User A.

In addition, connecting to the gateway via mstsc allows for a connection, regardless of User.

Has this occurred for anyone else? Any fixes or resolutions? Is this just a bizarre anomaly?