Collection2 doesn't clean data when using $push

I'm using collection2 to insert data from my form into my SimpleSchema. Collection2 is supposed to clean the data before insert, however, if I use $push to insert an array, the data isn't cleaned. All fields with no data contain "". As far as I'm aware it isn't possible to use $set which does clean the data. What am I missing?

Snippet: Schema

const ProfileCandidateSchema = new SimpleSchema({
  careerHistoryPositions: { type: Array, optional: true },
  'careerHistoryPositions.$': { type: Object, optional: true },
  'careerHistoryPositions.$.uniqueId': { type: String, optional: true },
  'careerHistoryPositions.$.company': { 
    type: String, 
    optional: true, 
    custom: function () {
      const shouldBeRequired = this.field('careerHistoryPositions.company').value;

      if (!shouldBeRequired) {
        // updates
        if (this.isSet) {
          if (this.operator === '$set' && this.value === null || this.value === '') return SimpleSchema.ErrorTypes.REQUIRED;
        }
      }
    }  
  }
}, {
  clean: {
    filter: true,
    autoConvert: true,
    removeEmptyStrings: true,
    trimStrings: true,
    getAutoValues: true,
    removeNullsFromArrays: true
  }
});

Snippet: Update

 const updatePosition = this.state.careerHistoryPositions.map((position) => {
      ProfileCandidate.update({
        _id: this.state.profileCandidateCollectionId
      }, {
        $push: {
          'careerHistoryPositions': {
            uniqueId: position.uniqueId,
            company: position.company
          }
        }
      });
    });

You can initialize an array with $set by using square brackets around the object to be inserted:

const updatePosition = this.state.careerHistoryPositions.map((position) => {
  ProfileCandidate.update(this.state.profileCandidateCollectionId, {
    $set: {
      careerHistoryPositions: [{
        uniqueId: position.uniqueId,
        company: position.company
      }]
    }
  });
});