This is really weird, but I tried to open up a new sticky note to paste in a link, and when I tried, the new sticky note started to flicker really fast and I can't right click, close it, or write on it or any other notes either. If I'm on the sticky notes, they won't let me go back to the thing I was on before. Also, the little keyboard icon (next to the battery and wifi connection icon) that tells you the language of your keyboard flickers at the same time. I really need to put some things on the sticky note! Can anyone help? Thanks!
Open the Keyboard in your sys pref.
The click on the Input sources Tab.
Uncheck the "Automatically switch to Document Input source".
If above did not work try following.
Delete it and restart.