Automapper ProjectTo not working with EFCore in memory database (unit tests)

We are using Automappers ProjectTo method to build a DTO object that is a subset of a larger database view. It is working as expected when running the actual application but we have had a problem where it doesn't give expected results when unit testing with an EF Core In-Memory database. It seems to just be giving back 0 results no matter what the query. Here is the test I am trying to run.

[Fact]
public async Task GetTemplateAdHocReportList_ReturnsOnlyTemplateReports()
{
    await TestHelper.SeedFull(ReportContext); // Calls SeedAdHocReports below along with other seed methods

    var results = await _sut.GetTemplateAdHocReports();

    results.Where(x => !x.IsTemplate).Count().Should().Be(0);
}

This is the Seed Data:

public static async Task SeedAdHocReports(ReportContext context)
{
    var reports = new AdHocReport[]
    {
        new AdHocReport()
        {
            Id = 1,
                Name = "DevExtreme Example Report",
                IsTemplate = true,
                AdHocDataSourceId = 1,
                Fields = "[{\"caption\":\"Category\",\"dataField\":\"ProductCategoryName\",\"expanded\":true,\"area\":\"row\"},{\"caption\":\"Subcategory\",\"dataField\":\"ProductSubcategoryName\",\"area\":\"row\"},{\"caption\":\"Product\",\"dataField\":\"ProductName\",\"area\":\"row\"},{\"caption\":\"Date\",\"dataField\":\"DateKey\",\"dataType\":\"date\",\"area\":\"column\"},{\"caption\":\"Amount\",\"dataField\":\"SalesAmount\",\"summaryType\":\"sum\",\"format\":{\"type\":\"currency\",\"precision\":2,\"currency\":\"USD\"},\"area\":\"data\"},{\"caption\":\"Store\",\"dataField\":\"StoreName\"},{\"caption\":\"Quantity\",\"dataField\":\"SalesQuantity\",\"summaryType\":\"sum\"},{\"caption\":\"Unit Price\",\"dataField\":\"UnitPrice\",\"format\":\"currency\",\"summaryType\":\"sum\"},{\"dataField\":\"Id\",\"visible\":false}]",
                Status = true
        }
    };

    context.AdHocReports.AddRange(reports);
    await context.SaveChangesAsync();
}

Here is the GetTemplateAdHocReports method being tested

public async Task<IList<AdHocReportDto>> GetTemplateAdHocReports()
{
    //This gives the expected 1 object in the unit tests:
    var test = await _reportContext.AdHocReports.Where(x => x.Status && x.IsTemplate).OrderBy(x => x.Name).ToListAsync();

    //This always comes back with a count of 0 even though the seed data should return 1 result
    var results = await _reportContext.AdHocReports.Where(x => x.Status && x.IsTemplate).OrderBy(x => x.Name).ProjectTo<AdHocReportDto>(_mapper.ConfigurationProvider).ToListAsync();
    return results;
}

Finally in case they are useful here are the constructors:

public AdHocServiceTests()
{
    TestHelper = new TestHelper();

    var reportOptions = TestHelper.GetMockedReportDbOptions();
    ReportContext = new ReportContext(reportOptions);

    _sut = new AdHocService(ReportContext, TestHelper.Mapper, TestHelper.GetMockedNiceService().Object);
}

public TestHelper()
{
    var mappingConfig = new MapperConfiguration(cfg =>
    {
        cfg.AddProfile<ReportDtoMapperProfile>();
    });
    Mapper = mappingConfig.CreateMapper(); // public property on TestHelper
}

public AdHocService(ReportContext reportContext, IMapper mapper, INiceService niceService)
{
    _niceService = niceService;
    _mapper = mapper;
    _reportContext = reportContext;
}

So the final question is why does the "var test = " line above work, but the following "var results =" line with the ProjectTo just keeps giving back 0 results?