Is it possible that you used a symbol form kicad’s 74xx library?
If yes: this library uses hidden pins for GND and VCC
You can connect them by turning on the visibility of hidden pins.
The approach intended by the original developers (not a good idea in my mind.):
Use the “correct” power symbols. Hidden power pins are comparable to global labels. The label name is the pin name.
So if you place a gnd power symbol all hidden power input pins named gnd are connected to this power symbol.
Best approach (the most work for you): make your own library by copying this one symbol and set the power pins to visible.
Or even better move them to their own unit such that you have your logic and power units separated. Example:
74vhc125mtcx_mu.lib (1.1 KB)
