[Waiting for user feedback] Repeated AMS / ATE authentication errors despite valid site keys

Hello,
I would like to report an issue we are currently facing with WPML AMS / ATE communication.
We are seeing the following error repeated hundreds of times in our debug.log:

WPML: Failed to send site key to AMS: AMS API returned false

We have verified that all our sites are correctly registered in our WPML account with valid site keys:

DEV
STAGE
PROD

You can confirm this here:
https://wpml.org/account/sites/

To troubleshoot, we also deregistered and re-registered the sites, but the issue persists.

In addition, we consistently see the following errors in:
/wp-admin/admin.php?page=wpml-tm-ate-log

Event: ATE Server Communication

Description: Unable to authenticate

Extra data:

{
"url": "hidden link",
"requestArgs": { "method": "GET" },
"status": "auth_error"
}

This confirms that the WordPress sites are able to reach WPML servers, but authentication with AMS / ATE is failing.

Could you please:

check if there is any issue with our account or site keys on your side,

verify if authentication tokens need to be refreshed or reset,

and advise on how to stop these repeated AMS / ATE authentication failures?

Thank you in advance for your help.