Why can I boot only Windows and not Ubuntu?

Solution 1:

Thanks to @oldfred for pointing me in the right direction. The solution was to boot into recovery mode (the only way I was able to get GRUB to show up was when dual-booting with Windows) and installing the latest graphics drivers. I followed this guide to install the drivers. https://linuxconfig.org/how-to-install-the-nvidia-drivers-on-ubuntu-20-04-focal-fossa-linux/ .Restarted and was able to boot into Ubuntu.