Do other reports work/render properly?

Are you 100% certain the data sources are set correctly? It's typical when deploying SSRS reports from BIDS to turn off the "overwrite data sources" option, are you certain it wasn't overwritten with an improper data source?

Also, check the execution log view on both reporting server's ReportServer databases to ensure you are seeing results for the production run - more specifically values in the bytecount and rowcount columns, as well as times in the Execution, Processing, and Render time columns.

Execution time is the duration the data set took to execute the SQL query against the data source, processing is the actual time taken for the report to process the data, and render time should be obvious.

You can use this query to troubleshoot (change as needed)/****** Script for SelectTopNRows command from SSMS ******/

SELECT TOP 1000

[ReportPath]

,[Format]

,[Parameters]

,[TimeStart]

,[TimeEnd]

,(TimeDataRetrieval * .001/60) [ExecutionTime(min)]

,([TimeProcessing] * .001/60) [ProcessingTime(min)]

,([TimeRendering] * .001/60) [RenderTime(min)]

,[ByteCount]

,[RowCount]

FROM [ReportServer].[dbo].[ExecutionLog2]

WHERE Source = 'LIVE' AND Status = 'rsSuccess'

AND ReportPath = 'YourReport'

ORDER BY TimeStart DESC