Altium warning: Adding items to hidden net +3.3V
Some Altium parts (mostly logic chips) have the supply and ground automatically connected to a supply net (you can spot these parts by their lack of visible power pins), I've never really understood the advantages, try putting a net label or something on a capacitor with the same names as the hidden nets and connect them to your existing power and ground rails as normal. Otherwise those pins might not get connected properly to the rest of the circuit. Altium will still compile with warnings though (one of my boards had several hundred warnings once because the schematic was in mm and the parts were in inches)