I've been using PowerBI for a while, and my reports(dashboards) are timing out now too. Never had an issue until this week(I was out of town last week, so I don't know when it actually started).

Ah, so it could be a Microsoft issue then.

I keep getting the attached error now, even though I’ve reduced the data set!

I just went to refresh the data on my reports so I could screenshot my error. Yesterday I was getting 502 bad gateway errors when it got to data for different objects (Computer 152, Device 98, etc). Today everything refreshed smoothly. We were also having issues with 502 errors enrolling wiped macbooks, hopefully those are gone now too...

I apparently spoke too soon. Now I've got the error back. It worked great for a couple of days....

OLE DB or ODBC error: [DataSource.Error] Web.Contents failed to get contents from 'https://<jamfcloudserver>/JSSResource/computergroups/id/13' (502): Bad Gateway.

And in a different query 

OLE DB or ODBC error: [DataSource.Error] Web.Contents failed to get contents from 'https://<jamfcloudserver>/JSSResource/mobiledevicegroups/id/10' (502): Bad Gateway.

I've managed to get it working today using the API rather than the PowerBi Connector....

I wonder if there is some throttling going on with the connector somewhere, but who knows