It seemed that everything was pointing to the fact that the MBR on Windows SSD somehow got erased, so I was able to recover it by following these steps: https://neosmart.net/wiki/fix-mbr/#Fix_the_MBR_in_Windows_10
Even then I had go through additional steps outlined after "If bootrec utility doesn’t fix it..."
After that, I had to change boot priority in BIOS to get to Ubuntu (because after following the steps in the link I provided it defaulted it to Windows) and in Ubuntu, I ran the commands that M.Yurizaki mentioned sudo os-prober and sudo update-grub. It detected Windows right away and I am now able to double boot.
Thanks, M.Yurizaki and Lukyp for your help.
What a relief, I came very close to reinstalling Windows entirely.