Copy Frames Option grayed out

[Rubie5FA1]

I am trying to copy the frames on my timeline, but the software prevents me from doing so. It's just a simple feature I've used before often, yet all of a sudden, it's unusable. Honestly have no idea why this software has so many random bugs for something that costs so much. I did literally nothing, even tried creating a blank project, and I still can't copy frames. 

[Joseph Labrecque]

Are the frames to be copied highlighted in blue? Is the layer unlocked?