Errors while refreshing dataflow

Same issue! 4 dataflows pulling from Salesforce and Excel, hourly refresh cadence, began failing yesterday at the 12:30AM scheduled refresh.

Spent all yesterday trying to troubleshoot, I was finally able to get everything running again, solution makes no sense but it's working for now. I hope this helps someone in the same predicament! 

My environment: 4 dataflows, the 1st pulls all the source data, the 3 following are Linked/Computed Entities. I am in a Premium workspace. Sources are Salesforce Objects & Excel. 

What I tried: Refreshing credentials, changing Privacy settings, switching gateways/gateway versions, importing the 1st dataflow as a new dataflow --- and it still failed. Finally, I took that source dataflow and imported it to a separate Premium Workspace - then it FINALLY refreshed!!! I was able to bring over the 3 reminaing/linked dataflows (importing JSON), and repoint their linked entities to the source dataflow (all in this separate Premium Workspace). The process was finicky and tedious but it finally worked. 1 Note - I did have to run it from the top (1st query kicks off 2, 3, & 4) in order for 2, 3 or 4 to refresh the first time around. 

The only thing different between the two workspaces is which capacity the workspace is assigned (we only have 2). The dataset consuming the dataflows is still in the orginal workspace and working fine. I asked our administator to move the second workspace to the same capacity as the orginal, and immediately the refresh failed. As soon as he switched the second workspace back to the other capacity, refreshes started working fine and ran hourly all night.

I cannot figure out what the issue is, my gut says this is related to metadata or authenication details stored in the metadata for this workspace? Perhaps a new capacity setting enabled by default? I would be great to find a solution, the dataflows still will not work in the original workspace and corresponding capacity