I'm trying to solder a TTP223 capacitive touch sensor to a USB switch (specifically a "UGREEN USB 3.0 Switch, 2 In 4 Output") to rig a sort of capacitive KVM switch to a desk PC I'm building, however I'm having trouble with it. It seems that when I connect the VCC and IO ports to the switch, it takes two presses of the button to work and I'm not entirely sure why. I've tried the same thing with a DisplayPort switch (CABLEDECONN DisplayPort 8K DP 1.4 Switch) and it works fine.
Apologies if I've missed any important details, this is my first real dive into anything electronics based, so I'm not even really sure how to go about debugging it. I haven't connected the ground wire to anything, and I'm not sure if it should be. Does anyone have any ideas of what may be the issue, or how I go about testing things?
EDIT: I've tested both boards with a multimeter, and the voltage over the DisplayPort board is 3V whereas the USB has 5V. I'm guessing this has an impact, but I'm not really sure what to do about it.