I flatten panels on the drum sander.
I believe what were talking about Is a board. Eliminating bow and twist is not the planers forte without a shimmed sled. The reference face of the board will become the other side. A twisted board through a planer will become a thinner twisted board.
I can sympathize. I recently had to declare that a project I was working on was needed to be scrapped and started over from zero because nothing was staying flat or square.
On the bright side, the remnants of the six board chest have been re-purposed, as it is the perfect size to hold scrap wood. If it were 2" shorter I could have turned it into a shoe rack for the front hallway, but that is not to be.
I hate to rub this in, but I had a great day in the shop. Made a drawer for a chess table. Cut the best half blind dovetails I have ever made. The drawer was the last thing I needed to complete. A little more scraping and sanding, should get the 1st coat of finish on it tomorrow.
Sorry about your poor results today ... yep, good day to just do some cleaning.