Predictive Routing: 500 Internal Server Error when Mapping Zendesk Tags to GC Skills via Platform API

The flexibility of GC is amazing, but I have hit a snag with the Platform API while setting up Predictive Routing.

In Zendesk, we used simple tags to route tickets to specific agent groups. I am trying to replicate this by creating Skills in GC and assigning them to agents, then using the Platform API to update agent profiles with these skills based on the incoming interaction data.

I am using the PATCH endpoint /v2/users/{id} to assign skills. However, I am receiving a 500 Internal Server Error with the message "Internal Server Error" in the response body. The request payload looks like this:

{
 "skills": [
 {
 "id": "abc-123-def-456",
 "level": 10
 }
 ]
}

I have verified that the skill ID exists in the eu-01 region and that the user has the admin role. In Zendesk, this was as simple as adding a tag. I am sure GC offers more granular control, but this error is blocking my migration progress.

Could this be related to the skill not being published yet? Or is there a specific permission required on the user object that I am missing? Any practical advice on mapping Zendesk tags to GC skills for Predictive Routing would be incredibly helpful. I am eager to get this working so we can leverage the advanced AI routing capabilities!