InsertBulkAsync<T> fails with error: Cannot change DataType of a column once it has data.

[Raxidi]

Firstly this is a great library and thanks a ton @schotime !!

I am facing with the issue with InsertBulkAsync where my poco class has nullable properties. I'm getting "Cannot change DataType of a column once it has data. : at System.Data.DataColumn.set_DataType(Type value)....." when InsertBulkAsync is called.

NPoco.SqlServer v.5.7.0

Here is the code snippet:

using(var transaction = db.GetTransaction())
{
    await db.InsertBulkAsync<MyClass>(listOfMyclassObjects);
}

and here is the poco class definition.

[TableName("MyTableName")]
[PrimaryKey("ID", AutoIncrement = true)]
public class MyClass
{
	[Column("ID")]
	public int ID { get; set; }

	[Column("TextID")]
	public string TextID { get; set; }

	[Column("DocID")]
	public string DocID { get; set; }

	[Column("DocumentName")]
	public string DocumentName { get; set; }

	[Column("PageNum")]
	public int? PageNum { get; set; }

	[Column("Label")]
	public string Label { get; set; }

	[Column("Value")]
	public string Value { get; set; }

	[Column("LabelID")]
	public int? LabelID { get; set; }

	[Column("SplitValue1")]
	public string SplitValue1 { get; set; }

	[Column("SplitValue2")]
	public string SplitValue2 { get; set; }

	[Column("SplitValue3")]
	public string SplitValue3 { get; set; }

	[Column("SplitValue4")]
	public string SplitValue4 { get; set; }

	[Column("SplitValue5")]
	public string SplitValue5 { get; set; }

	[Column("SplitValue6")]
	public string SplitValue6 { get; set; }

	[Column("FromOldBatch")]
	public bool? FromOldBatch { get; set; }
}

Am I doing anything wrong? Thanks a lot.

[Raxidi]

Update: Removing the transaction doesn't make any difference.