We were having the same issues with ME51N, but added the transaction configurations listed above and everything is working now.
However, I am not able to switch between tabs when in edit mode as shown in the demo vid. Instead, I have to pull fields out of a single tab, then save and exit, then switch to the next tab, then go back into edit mode and repeat the process for every subsequent tab. It's not really a flaw, just a convenience issue, so I wanted to mention it as an FYI to anyone else who was using the video as a guide.
Cheers!
Cheryl