Illlustrator CC 2018 - build 22.01

Document with 5 A4 workspaces side by side, adding a new A4 workspace makes Illustrator crash immediately. No saving, no warning no nothing ...
The only way I can find is making a new dociument with the number of pages you need and copy the artwork. Good luck if you have several layers, and you have to redo everything if you need one more page.