Strange search result nGram + Highlight

Since I added nGram to my index I have gained very strange search result. As far as I can see the index is correct, so I think it is my query that is wrong.

When I remove the Highlight part of the query I get what I belive is a correct search result, but when I add the part I get hits on just a very few things.

I have limited the number of fields to just two for debugging purpouses, and I have also tried to remove the whole field-list to get all fields.

I have also had highlights specified for all fields used, but that did not work either.

It is not the Filter part because I tested it before I started with nGram, and I have tried to remove it as well, making just a MultiMatchQuery.

Please, I feel I am going insane here. There must be some fundamental part I am missing.

        Explain = true,
        Size = 100,
        Sort = new List<ISort>
        {
            new FieldSort  { Field = "_score", Order = SortOrder.Descending },
        },
        Query = new BoolQuery
        {
            Must = new QueryContainer[] { new MultiMatchQuery
                {
                    Query = searchString,
                    Fields = new Field("email.content.subject").And("email.content.body"),
                    Type = TextQueryType.MostFields,
                }
            },
            Filter = new QueryContainer[] { new MatchQuery
                {
                    Field = "authority",
                    Query =  userauthority,
                    Operator = Operator.Or
                }
            },
        },
        Highlight = new Highlight  
        {
            PreTags = new[] { "###BEGINstrong###" },  
            PostTags = new[] { "###ENDstrong###" },
            Encoder = HighlighterEncoder.Html,
            BoundaryScanner = BoundaryScanner.Sentence,
            Fragmenter = HighlighterFragmenter.Span,
            NoMatchSize = 0,
            FragmentSize = 200,
            NumberOfFragments = 5,
            Fields = new Dictionary<Field, IHighlightField>
                             {
                                {
                                "*", new HighlightField 
                                    {

                                    }
                                }
                            }
        }