Maven artifact resolution for authenticated repositories doesn't work

When using a private maven repo (eg gitlab) Intellij will fail to resolve artifacts. It looks like it's not using my settings.xml file when trying to resolve the artifacts.

My specific setup - I've got a project which uses a parent pom, sourced from a private gitlab repo. 

Git authenticates using a http header, so you add the secret to a header in settings xml like so:

<settings>
  <servers>
    <server>
      <id>gitlab-maven</id>
      <configuration>
        <httpHeaders>
          <property>
            <name>Private-Token</name>
            <value>***************</value>
          </property>
        </httpHeaders>
      </configuration>
    </server>
  </servers>
</settings>

This works for maven builds when executing maven - from cli, Maven plugin in Intellij and so on. 

But - intellij says it can't resolve the parent and will display the following error:

Intellij will also report an error in Maven -> Repositories if I try to update the private repo - it shows "Error" in the Updated column.

Updating the local index (which does contain the parent) does not fix the problem -  it still doesn't show up as a valid dependency