How To Clear An Interrupt Flag On Arduino Zero

That schematic is wrong. That's an older version of the schematic from before Arduino.cc and Arduino.org split, and matches the M0 PRO by Arduino.org.

If you check pins 2 and 4, you will see those are reversed as well.

Adafruit has the correct schematics here:

I guess they posted the Eagle schematic because it is easier for beginners to read than the schematic from what I assume is Altium, but they really should have updated it to be accurate.