It's very likely some backend issue that Domo will need to take a look at. I'd recommend reaching out to Domo Support as they'd have more insight into the exact error that's occurring.

I would try and create a new redshift dataflow and copy in one step at a time and save and run it after each step to see if there is a particular step that causes the issue. This will help support out if you run into something and your syntax is something that the dataflow should be handling.