I am playing as a sorcerer -- mid-combat, when the sorcerer's turn came up, I did quicken spell + light, and planned on following it up with the spell scorching ray.
I see scorching ray is greyed out after I cast light.
According to D&D rules, I should still be able to use a spell slot with my action, if my bonus action was only a cantrip. I only expect the spells to be greyed out if I had used a spell slot for my bonus action!
See in this photo: Log in the top right shows all I did was quicken Light. Spells in the bottom left shows greyed out options.