notification bubble window misplaced once after reawakened from sleep mode

I am using Ubuntu Mate 20.04 LTS on an Acer Swift 3 with an external ViewSonic monitor. I noticed that the notification window, which usually appears in the top right corner of the screen, directly under the bar, is sometimes misplaced. Then it will appear in the top left corner, but shifted to the outside of the window so that only the right margin of the window is visible. This seems to happen seldomly and randomly, I originally thought, the first time the windows shows up after reawakening the notebook from sleep mode, but after testing I cannot confirm that. I include a partial screenshot.