Logitech K780 Frequently Asked Questions Manual page 22

When the device is paired in Unifying mode, it's not possible to perform keystroke

assignments.
If you encounter these issues, check to see if Secure Input is enabled on your system. Do
following:
1. Launch Terminal from /Applications/Utilities folder.
2. Type the following command in Terminal and press Enter:
ioreg -l -d 1 -w 0 | grep SecureInput

If the command returns back no information, then Secure Input is not enabled on the
system.

If the command returns back some information, then look for
"kCGSSessionSecureInputPID"=xxxx. The number xxxx points to the Process ID (PID)
of the application that has Secure Input enabled:
1. Launch Activity Monitor from /Applications/Utilities folder.
2. Search for PID which has secure input enabled.
Once you know which application has Secure Input enabled, close that application to resolve the
issues with Logitech Options.
 +K780 keyboard does not work or loses connection frequently

Keyboard isn't working

Keyboard frequently stops working

Before reconnecting your keyboard

Reconnect your keyboard
Keyboard isn't working
In order for your keyboard to work with your device, the device must have built-in Bluetooth
capability or be using a third-party Bluetooth receiver or dongle.
NOTE: The K780 keyboard isn't compatible with a Logitech Unifying receiver, which uses
Logitech Unifying wireless technology.
If your system is Bluetooth-capable and the keyboard isn't working, the problem is likely a lost
connection. The connection between the K780 keyboard and the computer or tablet can be lost
for several reasons, such as:

Low battery power

Using your wireless keyboard on metal surfaces

Radio frequency (RF) interference from other wireless devices, such as:
o Wireless speakers
o
Computer power supplies
o Monitors
o
Cell phones