Also experiencing this issue with a table I obtained by running summary statistics on a feature's attribute table. It's a small table with simple data. When running the Table to Excel tool, the process hangs up on "Running..." and never completes. Pressing the Cancel button then hangs up on "Cancelling..." and I cannot run anymore geoprocessing tasks because the que is stuck.
Replicated this using a different feature and a different file destination with an uncomplicated naming convention.
Screenshot shows pop-out window when I choose View Details. Has been running/cancelling for 10 minutes.