You should use the most recent screensaver build:
https://www.mobileread.com/forums/sho...d.php?t=225030
Get your python package from the same place.
The "fix images" option most likely requires it.
Did you change your picture's dimensions to fit the higher resolution screen?
Move your current /mnt/us/temp.png to the screensaver's directory -
Let it go to sleep and make sure the picture works with your Kindle.
If not, try the "fix all images" option of the new screensaver package and try it again by letting it go to sleep.
If it works on the second try, you will need to correct your image generation.
If none of the above helps, tell us the firmware version you are using and if it is a factory or consumer version firmware.