Highlight does not work properly with ScriptScore, version 7.8

[gurjit_buck (Gurjit Singh)]

Elasticsearch version (7.8):

OS version (Windows 10):

Along with ScriptScore function, Highlight function does not work properly. If we search two words only first word gets higlighted or last word doesn't display highlighted:

Eg. Doc content- this is a boy
On searching - this is
Output content shows only 'this' as highlighted

       var searchResponse = await elasticClient.SearchAsync<Document>(body => body

           .Index(Settings.Index + "-*")
                 .Query(qx =>


                         qx.ScriptScore(fx => fx
                   .Query(qt =>

                    qt.Bool
                  (bb => bb.Must(q =>
                     q.MatchPhrasePrefix(m => m.Field(f => f.Content).Query(req.SearchText)))  // q.Terms(c => c.Field(p => p.Tags).Terms(words))

                   ) 
    )
                    .Script(w => w.Source("String gmtString = params.searchdate;ZonedDateTime zdt = ZonedDateTime.parse(gmtString,DateTimeFormatter.RFC_1123_DATE_TIME);ZonedDateTime zdt2 =ZonedDateTime.of(doc['date'].value.year,doc['date'].value.monthOfYear,doc['date'].value.dayOfMonth,doc['date'].value.hourOfDay,doc['date'].value.minuteOfHour,doc['date'].value.secondOfMinute, 0, ZoneId.of('Z')); if (zdt2.toInstant().toEpochMilli()==zdt.toInstant().toEpochMilli()){return 100;}else{return _score;} ").Params(par))) 

           ).Highlight(h => h.Fields(
                 fs => fs
        .Field(p => p.Content)
           .NumberOfFragments(0),
     fs => fs
        .Field(p => p.Attachment.Content).NumberOfFragments(0).Type(HighlighterType.Unified)
        ).PreTags("<b>").PostTags("</b>")));
 

Please suggest any solution