Can't copy, paste, etc after a few minutes of use on 2.0.3

I can’t edit or do much of anything with Audacity after a few minutes of using it. Right when I open a file in Audacity, I can highlight, copy, paste, delete the selected sound. But after a few minutes of using it, if that, the option of copy, paste, etc is not available. Not available in the Edit menu, nor by keyboard command. Anyone have this problem or know how I can fix it?

Click the “Stop” button.
Most functions are disabled when playing, recording or paused.