Parameters and Power Apps

I have followed the steps in the Microsoft documentation for creating a Power App embedded in a Power BI report that filters the Power App using the Power BI Field. (Power Apps visual for Power BI - Power Apps | Microsoft Docs)

The data doesn't filter, I have 'proven' the filters for items works by testing it hardcoded to load one record, so I know the app works.  It doesn't seem to read in the parameter from Power BI.  I have the field set in Power BI on the Power App visual and the code for items in the PowerApp gallary is as follows:

LookUp(funds_received_large,Client_matter_number=First(PowerBIIntegration.Data).Client_matter_number)

If I hard code it, the data does load, eg: LookUp(funds_received_large,Client_matter_number="1")

Field in Power BI Power App visual:

Items in Power App:

Any help would be appreciated!