For the K400+ wireless keyboard, when the keyboard has been powered off for about 30 minutes and powered back on, the keys are unresponsive for about 10 seconds while the touchpad and mouse buttons are responsive immediately. This persists across USB ports and multiple devices I've used the keyboard with (Windows 11 PC, LG OLED C2, and Valve Steamdeck). Since the keys are responsive when powering off and on in a shorter timeframe it seems to be something in the firmware of the unifying receiver. If this is a power-saving feature that could be toggled on and off it would be great if this could be toggled in Options+ or remedied in a firmware update so the change persists across devices.