I purchased a USB keyboard with a numeric keypad to avoid the frequent battery replacements required by my Bluetooth keyboard. However, after upgrading to the latest version of macOS El Capitan, the keyboard stopped waking from sleep mode and became completely unresponsive.
None of the solutions suggested on Apple Support forums resolved the issue, including:
– Connecting the keyboard to different USB ports and removing other USB devices
– Disconnecting and reconnecting the keyboard after several minutes
– Resetting NVRAM and other macOS system settings
Solution:
Although it may seem illogical, connecting the keyboard to the MacBook Pro through a USB extension cable immediately resolved the issue.
If you encounter the same problem, this workaround is worth trying :-)