I seem to have a similar problem to the one scferg5 posted here.
I have a Logitech K830 wireless keyboard and touchpad combo that worked fine when connected through the Logitech Unifying USB receiver until some time around Jan 2019.
After a Windows update the typing part (i.e. including Windows key, escape, arrow keys etc., but not function keys like mute, suspend etc.) of the device suddenly stopped working, while the touchpad and the aforementioned function keys still worked fine.
The device still works via Unifying receiver on a Linux OS on the same machine; it also still works on Windows when connected via bluetooth.
I have done everything that was suggested in scferg5s post, i.e. toggled ease of access filter keys and rebooted and re-installed the Logitech software; furthermore I have used a different receiver with the same result and tried to install the Windows stand alone update KB4090913 which was referenced on the Logitech support site here, which Windows did not allow me to install ("not applicable to my Windows" or sth).
What could it be?
Best Answer
I've ordered and plugged in a new Unifying receiver and got an error message upon Windows auto-install that there was a driver issue. I manually selected the driver, following @harrymc's advice not using the Logitech provided driver but rather the Windows default one, et voilà! it is working.
Thanks for your help, guys!