Can confirm this behavior in my tenant - when editing dataflows the gateway bind seems to be forgotten
The fix for us has been to have dataflow editors go to Project Options to select the gateway and then configure connections again. The expected behavior is that the dataflow editor would not have to rebind to the gateway each time they are editing.
We can also concur that this issue has arisen within the past 24 hours...first noticed midday on 15/2/2021. Scheduled dataflows still work.
Within the Web Power Query Editor, all three of our developers see the "Edit Credentials" button. Each of us can edit the Project Options and choose our On-premises data gateway but the change is not saved and the issue recurs.
I am seeing this in three of my clients' tenants. All are using gateways to connect to SQL views. The dataflows continue to refresh as scheduled. However, when using in the dataflow query editor the connections are broken. Specifically it gives the warning "Please specify how to connect." along with a "Configure Connection" button. All was working fine last week.
All dataflows are connecting to the SQL views using a ‘Basic’ authentication method with username and password. Any attempt to re-configure the connection while in the editor fails with “We uncounted an unexpected error”.
To try and resolve the issue I re-built a dataflow from scratch and it worked – I could connect to the data, build the queries, save the dataflow and refresh it. But it fell over again as soon as I attempted to edit it. Note: copying queries, or importing dataflow .json files didn’t work at all.
Power BI customers editing existing dataflows that use the on-premises gateway client may see the message, "Please specify how to connect". Any changes made will not be saved. Engineers have identified the root cause and a fix is expected to be deployed by end-of-day 02/22/2021
