Same problem here since AI 2021. I work around it by saving the document with rulers off, then closing and reopening it. A second workaround works for me, too: turn rulers off, open a new window (Window -> New Window) with the same document then close the original window. As long as this bug exists, Illustrator 2021 for me is not really useable at all. Until then I will use Illustrator 2020. (iMac 27 2019, Radeon Pro 580 X, 64 GB RAM, OS X 10.15.7 Catalina)
Same problem here since AI 2021. I work around it by saving the document with rulers off, then closing and reopening it. A second workaround works for me, too: turn rulers off, open a new window (Window -> New Window) with the same document then close the original window. As long as this bug exists, Illustrator 2021 for me is not really useable at all. Until then I will use Illustrator 2020. (iMac 27 2019, Radeon Pro 580 X, 64 GB RAM, OS X 10.15.7 Catalina)