Slider Revolution Copy-Paste layer using keyboard shortcuts not working

In Safari and Firefox the browser keyboard shortcut menu items (⌘-C and ⌘-V) are greyed out when trying to copy-paste layers in Slider Revolution.

Slider Revolution's own menu within the browser works fine when selecting with the mouse and despite indicating either ⌘-C and ⌘-V or ⌥ ⇧ C and ⌥ ⇧ V are the correct keyboard shortcuts, they do not work.

Chrome works fine but would rather stick with one of the two aforementioned browsers or at least understand what the issue is. Anyone know what is accusing this or if there is a way to enable?