Want to create a nest query to filter on optional field

[tony_sid]

{
	{
		"id": 8,
                "teamId": 0,
                "experience": 1,
		"companyName": "MyCompany"
	},
	{
		"id": 9,
                "teamId": 0,
                "experience": 1,
	},
	{
		"id": 10,
                "teamId": 1,
                "experience": 1,
	},
	{
		"id": 11,
                "teamId": 1,
                "experience": 1,
	        "companyName": "MyCompany"
	}
}

// Here is my nest query

List<Func<QueryContainerDescriptor<SearchClass>, QueryContainer>> filters = new List<Func<QueryContainerDescriptor<SearchClass>, QueryContainer>>();
filters.Add(n => n.Term(trm => trm.CompanyName.ToLower(), companyName.ToLower()))

jobProfiles = await _searchClient.SearchAsync<JobProfileSearch>(descriptor => descriptor
                    .From(pageIndex == 0 ? pageIndex : pageIndex * pageSize)
                    .Size(pageSize)
                    .Query(q => q
                        .Exists(e => e.Field(p => p.CompanyName)))
                    .PostFilter(q => q
                        .QueryString(queryDescriptor => queryDescriptor
                           .Query($"*{searchString}*")
                           .Fields(fs => fs
                           .Field(p => p.experience, 10)
                           .Field(p => p.IndustryType, 5)
                           .Field(p => p.SubIndustryType, 3)))
                        )
                    .PostFilter(q => q.Bool(bq => bq.Filter(filters))));

When i try to apply this i am not getting any result. My need is to search for company name from object where company name exist