How to make EF core translate custom sort into a plain 'When Then' instead of hierarchical

The problem is - I get the following errror:

Case expressions may only be nested to level 10.

when I try using the following LINQ code with EF core

var extendedResult = result.Select(p => new
    {
        readModelFields = p,
        sortKey =
            p.CaseState == CaseState.Scheduled.ToString() ? 1 :
            p.CaseState == CaseState.Queued.ToString() ? 2 :
            p.CaseState == "Investigation" ? 3 :
            p.CaseState == "Awaiting Customer" ? 4 :
            p.CaseState == "State 5" ? 5 :
            p.CaseState == "State 6" ? 6 :
            p.CaseState == "State 7" ? 7 :
            p.CaseState == "State 8" ? 8 :
            p.CaseState == "State 9" ? 9 :
            p.CaseState == "State 10" ? 10 :
            p.CaseState == "State 11" ? 11 :
            p.CaseState == "Rejected" ? 12 :
            p.CaseState == "Blocked" ? 13 :
            p.CaseState == "Postponed" ? 14 :
            15
    });

    return IsAscending(query.SortDirection)
        ? extendedResult.OrderBy(p => p.sortKey).Select(p => p.readModelFields)
        : extendedResult.OrderByDescending(p => p.sortKey).Select(p => p.readModelFields);

And the issue is caused by the way SQL genertes SQL (here's a result)

exec sp_executesql N'SELECT [o].[Id], [o].[Owner], [o].[CaseState],  [o].[LastActionDate], [o].[CountryCode], [o].[Name], [o].[Risk]
FROM [dbo].[OpenCases] AS [o]
ORDER BY CASE
    WHEN [o].[CaseState] = N''Scheduled'' THEN 1
    ELSE CASE
        WHEN [o].[CaseState] = N''Queued'' THEN 2
        ELSE CASE
            WHEN [o].[CaseState] = N''Investigation'' THEN 3
            ELSE CASE
                WHEN [o].[CaseState] = N''Awaiting Customer'' THEN 4
                ELSE CASE
                    WHEN [o].[CaseState] = N''State 6'' THEN 6
                    ELSE CASE
                        WHEN [o].[CaseState] = N''State 7'' THEN 7
                        ELSE CASE
                            WHEN [o].[CaseState] = N''State 8'' THEN 8
                            ELSE CASE
                                WHEN [o].[CaseState] = N''State 9'' THEN 9
                                ELSE CASE
                                    WHEN [o].[CaseState] = N''State 10'' THEN 10
                                    ELSE CASE
                                        WHEN [o].[CaseState] = N''State 11'' THEN 11
                                        ELSE CASE
                                            WHEN [o].[CaseState] = N''Rejected'' THEN 12
                                            ELSE CASE
                                                WHEN [o].[CaseState] = N''Blocked'' THEN 13
                                                ELSE CASE
                                                    WHEN [o].[CaseState] = N''Postponed'' THEN 14
                                                    ELSE 15
                                                END
                                            END
                                        END
                                    END
                                END
                            END
                        END
                    END
                END
            END
        END
    END
END DESC
OFFSET @__p_0 ROWS FETCH NEXT @__p_1 ROWS ONLY',N'@__p_0 int,@__p_1 int',@__p_0=0,@__p_1=2147483647

What I want instead - is EF to build a query like this:

...
ORDER BY 
CASE
   WHEN CaseState = "Investigation" THEN 3
   WHEN CaseState = "State 5" THEN 5
   WHEN CaseState = "State 6" THEN 6
   WHEN CaseState = "State 7" THEN 7
   .......
   WHEN CaseState = "Postponed" THEN 14
END desc