Shortcut Key cntl macro box

Question

This problem is only on one computer using a shared document. My second computer does not have this problem, thus thinking I have hit something that has triggered this problem. When I record a macro, I add the Macro name but when clicking in the shortcut key field, the box alternates blinking black and white. I cannot enter any value in this field. I have to go to a second computer, enter the macro, then come back to my original computer to finish the macro. My main computer is an HP Envy and my second computer is a MS Surface. Thanks in advance!