Explanation of Issue
Eos family face panels use elastomer light blockers around the switches to prevent light bleed to other keys. These rubber light blockers can sometimes get loose in shipping or if the console is stored with the rear of the console facing down.
If the rubber pieces below the key caps did get knocked loose in shipping, repeatedly tapping that key while the console is sitting on a flat surface with the keyboard facing up can usually force the light blocker back in place.
If repeatedly tapping that key does not resolve the issue, the light blocker may be in the incorrect orientation.