US English keyboard layout produces wrong characters

I am using a wireless Logitech K750 solar keyboard (with USB unifying receiver instead of Bluetooth) with my late 2009 27" iMac running MacOS High Sierra. I had not used this computer in a while but today after installing the latest security update, I noticed that typing Shift-9 to get "(" would actually produce a ")" character! Other keys in that area are wrong as well. I verified "U.S." is correctly chosen in System Preferences > Keyboard and chosen in the menubar as well.. U.S. International PC produces wrong characters too. But "Australian" works as expected. I've never experienced that before with any keyboard. How do I fix this problem with the US English keyboard layout?

Thank you.