I remapped the caps lock key two ways.
I'm using a Mac, so in System Preferences, I have the Keyboard Modifier keys setup so that Caps Lock Key is Control. I do this because I use the laptop keyboard as well as other keyboards.
On the FC660C, I have Dip Switches 1 and 2 set to ON, and 3 and 4 set to OFF. Dip Switch 1 should allow Caps Lock to behave as Control.
I have no custom software to map keys. I have multiple MBP, and it happens on both of them. It also does it on my iMac Pro.
What I have found was pressing the Left Ctrl (in the lower left corner) and the Caps Lock key (which is mapped to Ctrl) will toggle Caps Lock on and off.