@generix - thank you very much for your help. Your instructions above for removing and re-installing the nvidia kernel modules worked for me.
I did make one change to the commands you cited above.
When I ran the dkms install command, I got quite a few messages like this:
Good news! Module version 460.39 for nvidia.ko
exactly matches what is already found in kernel 5.8.0-45-generic.
DKMS will not replace this module.
You may override by specifying --force.
So I decided to install the kernel modules using the --force option to make sure they got updated. That seemed to work. Here are the commands that I ran:
sudo dkms remove nvidia/460.39 --all
sudo dkms install --force nvidia/460.39 -k $(uname -r)
sudo update-initramfs -u
sync
reboot
Thank you again for all of your help!