GroupJoin with incorrect data

This is indeed a bug in LINQ-to-SQL.

I've included a fix in 9.10.2. It now translates

HeapOuters.GroupJoin (
    HeapInners, 
    o => o.Id,
    i => i.IdOuter,
    (o, ins) => new { o.Id, Items = ins.ToList () }
)

to

SELECT [t1].[Id], [t2].[IdOuter], [t2].[Tipo], [t2].[Amount], (
    SELECT COUNT(*)
    FROM (
        SELECT NULL AS [EMPTY]
        FROM [HeapInner] AS [t3]
        WHERE [t1].[Id] = [t3].[IdOuter]
        ) AS [t4]
    ) AS [value]
FROM (
    SELECT ROW_NUMBER() OVER (ORDER BY [t0].[Id], [t0].[Name]) AS [ROW_NUMBER], [t0].[Id]
    FROM [HeapOuter] AS [t0]
    ) AS [t1]
LEFT OUTER JOIN [HeapInner] AS [t2] ON [t1].[Id] = [t2].[IdOuter]
ORDER BY [t1].[ROW_NUMBER]

Let me know how you get on.