Yesterday I tried to print a Picture Package but when the Print window opened there was a tiny image on display.
After clicking "Scale to Fit Media" the image jumped to its correct size but was grossly pixelated as shown in the screenshot.

I only use PS very occasionally and remembered that this had occurred a couple of years ago.
The "cure" that I discovered was to click the "Done" button and close the window.
On re-opening the window the picture was displayed properly.
It would appear that I am doing something wrong in the first place to create this pixelated effect.
So how can I stop it happening again?