StringAsEnumResolver not working

Using latest 8.0.0-rc3.

services.AddControllers()
    .AddOData(opt => opt.Count().Filter().Expand().Select().OrderBy().SetMaxTop(100)
        .AddModel(string.Empty, GetEdmModel(),
            builder =>
            {
                builder.AddService(Microsoft.OData.ServiceLifetime.Singleton, typeof(ODataUriResolver), sp => new StringAsEnumResolver() { EnableCaseInsensitive = true });
            })
        .Conventions.Add(new OdataConvention()))

With the above code to configure StringAsEnumResolver, I'm still not able to use strings to filter enums. I've scoured the internet to no avail.

What am I missing?

Error from $filter=contactType eq 'person':

{
  "error": {
    "code": "",
    "message": "The query specified in the URI is not valid. The string 'person' is not a valid enumeration type constant.",
    "details": [
      
    ],
    "innererror": {
      "message": "The string 'person' is not a valid enumeration type constant.",
      "type": "Microsoft.OData.ODataException",
      "stacktrace": "   at Microsoft.OData.UriParser.MetadataBindingUtils.ConvertToTypeIfNeeded(SingleValueNode source, IEdmTypeReference targetTypeReference)\n   at Microsoft.OData.UriParser.BinaryOperatorBinder.PromoteOperandTypes(BinaryOperatorKind binaryOperatorKind, SingleValueNode& left, SingleValueNode& right, TypeFacetsPromotionRules facetsPromotionRules)\n   at Microsoft.OData.UriParser.ODataUriResolver.PromoteBinaryOperandTypes(BinaryOperatorKind binaryOperatorKind, SingleValueNode& leftNode, SingleValueNode& rightNode, IEdmTypeReference& typeReference)\n   at Microsoft.OData.UriParser.StringAsEnumResolver.PromoteBinaryOperandTypes(BinaryOperatorKind binaryOperatorKind, SingleValueNode& leftNode, SingleValueNode& rightNode, IEdmTypeReference& typeReference)\n   at Microsoft.OData.UriParser.BinaryOperatorBinder.BindBinaryOperator(BinaryOperatorToken binaryOperatorToken)\n   at Microsoft.OData.UriParser.MetadataBinder.BindBinaryOperator(BinaryOperatorToken binaryOperatorToken)\n   at Microsoft.OData.UriParser.MetadataBinder.Bind(QueryToken token)\n   at Microsoft.OData.UriParser.FilterBinder.BindFilter(QueryToken filter)\n   at Microsoft.OData.UriParser.ODataQueryOptionParser.ParseFilterImplementation(String filter, ODataUriParserConfiguration configuration, ODataPathInfo odataPathInfo)\n   at Microsoft.OData.UriParser.ODataQueryOptionParser.ParseFilter()\n   at Microsoft.AspNetCore.OData.Query.FilterQueryOption.get_FilterClause()\n   at Microsoft.AspNetCore.OData.Query.Validator.FilterQueryValidator.Validate(FilterQueryOption filterQueryOption, ODataValidationSettings settings)\n   at Microsoft.AspNetCore.OData.Query.FilterQueryOption.Validate(ODataValidationSettings validationSettings)\n   at Microsoft.AspNetCore.OData.Query.Validator.ODataQueryValidator.Validate(ODataQueryOptions options, ODataValidationSettings validationSettings)\n   at Microsoft.AspNetCore.OData.Query.ODataQueryOptions.Validate(ODataValidationSettings validationSettings)\n   at Microsoft.AspNetCore.OData.Query.EnableQueryAttribute.ValidateQuery(HttpRequest request, ODataQueryOptions queryOptions)\n   at Microsoft.AspNetCore.OData.Query.EnableQueryAttribute.OnActionExecuting(ActionExecutingContext actionExecutingContext)"
    }
  }
}

Error from $filter=contains(tolower(contactType),'person'):

{
  "error": {
    "code": "",
    "message": "The query specified in the URI is not valid. No function signature for the function with name 'tolower' matches the specified arguments. The function signatures considered are: tolower(Edm.String Nullable=true).",
    "details": [
      
    ],
    "innererror": {
      "message": "No function signature for the function with name 'tolower' matches the specified arguments. The function signatures considered are: tolower(Edm.String Nullable=true).",
      "type": "Microsoft.OData.ODataException",
      "stacktrace": "   at Microsoft.OData.UriParser.FunctionCallBinder.MatchSignatureToUriFunction(String functionCallToken, SingleValueNode[] argumentNodes, IList`1 nameSignatures)\n   at Microsoft.OData.UriParser.FunctionCallBinder.BindAsUriFunction(FunctionCallToken functionCallToken, List`1 argumentNodes)\n   at Microsoft.OData.UriParser.FunctionCallBinder.BindFunctionCall(FunctionCallToken functionCallToken)\n   at Microsoft.OData.UriParser.MetadataBinder.BindFunctionCall(FunctionCallToken functionCallToken)\n   at Microsoft.OData.UriParser.MetadataBinder.Bind(QueryToken token)\n   at Microsoft.OData.UriParser.MetadataBinder.BindFunctionParameter(FunctionParameterToken token)\n   at Microsoft.OData.UriParser.MetadataBinder.Bind(QueryToken token)\n   at Microsoft.OData.UriParser.FunctionCallBinder.<BindFunctionCall>b__7_0(FunctionParameterToken ar)\n   at System.Linq.Enumerable.SelectEnumerableIterator`2.MoveNext()\n   at System.Collections.Generic.List`1..ctor(IEnumerable`1 collection)\n   at Microsoft.OData.UriParser.FunctionCallBinder.BindFunctionCall(FunctionCallToken functionCallToken)\n   at Microsoft.OData.UriParser.MetadataBinder.BindFunctionCall(FunctionCallToken functionCallToken)\n   at Microsoft.OData.UriParser.MetadataBinder.Bind(QueryToken token)\n   at Microsoft.OData.UriParser.FilterBinder.BindFilter(QueryToken filter)\n   at Microsoft.OData.UriParser.ODataQueryOptionParser.ParseFilterImplementation(String filter, ODataUriParserConfiguration configuration, ODataPathInfo odataPathInfo)\n   at Microsoft.OData.UriParser.ODataQueryOptionParser.ParseFilter()\n   at Microsoft.AspNetCore.OData.Query.FilterQueryOption.get_FilterClause()\n   at Microsoft.AspNetCore.OData.Query.Validator.FilterQueryValidator.Validate(FilterQueryOption filterQueryOption, ODataValidationSettings settings)\n   at Microsoft.AspNetCore.OData.Query.FilterQueryOption.Validate(ODataValidationSettings validationSettings)\n   at Microsoft.AspNetCore.OData.Query.Validator.ODataQueryValidator.Validate(ODataQueryOptions options, ODataValidationSettings validationSettings)\n   at Microsoft.AspNetCore.OData.Query.ODataQueryOptions.Validate(ODataValidationSettings validationSettings)\n   at Microsoft.AspNetCore.OData.Query.EnableQueryAttribute.ValidateQuery(HttpRequest request, ODataQueryOptions queryOptions)\n   at Microsoft.AspNetCore.OData.Query.EnableQueryAttribute.OnActionExecuting(ActionExecutingContext actionExecutingContext)"
    }
  }
}

Start with the StringAsEnumResolver configuration in the issue and trace the reported calls through ODataUriResolver, StringAsEnumResolver, and ODataQueryOptionParser. Reproduce both filter expressions, then determine why the configured resolver does not accept the enum string and verify the supported behavior or fix.