Dataflow Refresh error message: Information is needed in order to combine data on merge

Hi, 

I have 2 tables in a dataflow. The data for both of them is coming from the same sharepoint and I have marked the privacy settings as "Organisational". 

Both refresh fine individually, but as soon as I try to merge them, the refresh fails with the following error

"Information is needed in order to combine data"

Looking around on similar threads here, I know that this is because of the privacy level settings. However, I can't seem to fix it. 

Does anyone have any idea why Dataflows fail when I try to merge 2 tables due to privacy issue