Dapper MultiQuery only returning the first match about dapper

[baynezy]

So in the end I worked it out. I did the following based on https://www.learndapper.com/relationships

var documents = await connection.QueryAsync<DocumentDto, LabelDto, CollaboratorDto, DocumentDto>(
            GetDocumentSql,
            (doc, label, collaborator) => {
                if (label is not null && label.LabelId != Guid.Empty) // empty guid means no label
                {
                    doc.Labels.Add(label);
                }
                if (collaborator.ProfileId != Guid.Empty) // empty guid means no collaborator
                {
                    doc.Collaborators.Add(collaborator);
                }
                return doc;
            }, 
            new
            {
                Id = documentId.ToString()
            },
            splitOn: "LabelId,DocumentId");
        
        var result = documents
            .GroupBy(d => d.Id)
            .Select(g =>
        {
            var groupedDocument = g.First();
            groupedDocument.Labels = g.Select(d => d.Labels.Single())
                .GroupBy(l => l.LabelId)
                .Select(l=> l.First())
                .ToList();
            groupedDocument.Collaborators = g.Select(d => d.Collaborators.Single())
                .GroupBy(c => c.ProfileId)
                .Select(c => c.First())
                .ToList();
            return groupedDocument;
        });

I am not in love with the catalogue of LINQ, but it does exactly what I need.