Basically, it boils down to, the C# driver can handle dynamic value = Guid.Parse("6cd6f392-8271-49bb-8564-e584ddf48890"), but it cannot handle List<dynamic> value = new List<dynamic> { Guid.Parse("6cd6f392-8271-49bb-8564-e584ddf48890"), Guid.Parse("c7b1ebaf-4ac1-4fe0-b066-1282e072585a") }.