Here is the fix: run following three commands in your terminal:
sudo systemctl enable nvidia-suspend.service
sudo systemctl enable nvidia-hibernate.service
sudo systemctl enable nvidia-resume.service
then: cd /lib/modprobe.d
sudo nano systemd.conf
Add following line at the end of the file:
options nvidia NVreg_PreserveVideoMemoryAllocations=1
CTRL-X and save
Then update (rebuild) kernel boot images
When using default systemd-boot and dracut:
sudo reinstall-kernels
When using Grub and dracut:
sudo dracut-rebuild