belongsTo relationship empty on save

I have two models that have a relationship, team and teamMember. On a page I'm trying to set it up so that the user can add a new teamMember to a team, but when I'm calling save() it's spitting back that a team must exist, and upon further inspection Ember is not embedding the team in the POST.

team.js

export default DS.Model.extend({
  ...
  teamMember: DS.hasMany('team-member')
}

team-member.js

export default DS.Model.extend({
  ...
  team: DS.belongsTo('team')
}

This is what I have in my route

let teamMember = this.get('store').createRecord('teamMember');
let team = this.get('store').findRecord('team', params.teamId).then((results) => {
  teamMember.set('team', results);

  return results;
});

I pass the team and the teamMember to a component where I can edit the teamMember, and save it.

let teamMember = this.get('teamMember');
// get and set teamMember specific fields
teamMember.save();

When I debug from that line I can say teamMember.get('team') and get all of the data, so it seems to be properly set, but all I get from the Rails API is

{"team_member"=>{"role_id"=>"0", "phone_number"=>"8888888888"}}

And it obviously won't create a team_member without a team to associate it with.

I have a team-member.js serializer:

export default ApplicationSerializer.extend(DS.EmbeddedRecordsMixin, {
  attrs: {
    team: { embedded: 'always' }
  }
});

I do have some stuff in an application serializer, so I'm wondering if it's overwriting the data somehow, but when I debug in that it's still not recognizing the existence of the team.