Mashup Exception Expression Error DataFlows 2 Gen

Hello!

I'm trying to transform and load data in dataflow 2 gen.
The dataflow is published but the error occurs while updating:

"The error code: Mashup Exception Expression Error: Couldn't refresh the entity because of an issue with the mashup document MashupException.Error: Expression.Error: The table could not be inserted., InnerException: Cannot convert a List type value to a Text type"

In that query there are the following steps:

1. Source (SharePoint.Tables...)
2. Navigation
3. Table.ExpandListColumn(Navigation, "PO")
4. Table.ExpandRecordColumn(#"Expanded: PO", "PO", {"lookupValue"}, {"Project Office"})
5. Table.ExpandListColumn(#"Expanded: PO 1", "Contractor")
6. Table.ExpandRecordColumn(#"Expanded: Contractor", "Contractor", {"lookupValue"}, {"Contractor"})

and so on

The columns Project office and Contractor are LookUp columns that consist of only one text value each (while creating table people choose one text value from a list for one table record). So that the type that I set for these columns is Text.

Could you please explain to me what the problem can be in my case?