This is actually for Notebook 21.0; apparently your form is quite out of date.

If I copy something (an image, text block, etc.) from one notebook file to paste into another, but close the first, the clipboard data is lost. That's not how this works for basically every other program I have used in the last 30 years. It is infuriating. Saving a file after copying does the same thing; why would I lose clipboard data by saving the file I copied from? It's been like this for a long time, and it irritates me at least once a week when I forget that I should NOT save my work in order to do things with your software.

I am using your software on a Macbook Air running Big Sur.