The Data Source Processing pane is showing the “loading icon” for 30 seconds

The Data Source Processing pane is showing the “loading icon” for 30 seconds then a timeout expired error message pops up and a log entry is written to the ErrorLog in the database. The message is: «XBI__GP_Get_Executables An error occurred while executing the command definition. See the inner exception for details. Timeout expired. The timeout period elapsed prior to completion of the operation or the server is not responding.»

Answer:
The reason for the timeout is a block/lock in XBI__GP_Create_All_DataBases. Use The SQL Server activity monitor to find which task is causing the lock. Kill the task if appropriate to release the lock.