SJ-12 is for enabling the pullup resistor on D10. SJ-1 is for changing the square wave alarm signal from the RealTimeClock from A7 (default) to D10. As stated on the Jumper Settings page (https://envirodiy.org/mayfly/hardware/jumper-settings/), you should never use SJ-12 if you’ve also changed SJ-1 to D10. The two can’t be used together or it will cause problems.
So remove your solder bridge on SJ-1 and put it back to the default setting by connecting the middle pad to the one labeled “A7”. Then have your sketch look for a LOW pulse on D10 by using this line:
attachInterrupt(2, tip, LOW);
Then anytime you get a tip by the bucket (assuming you connect D10 and GND to the two NormallyOpen poles of you rain gauge switch, the Mayfly will go into the “tip” function. If you still need help, I can post an entire sketch for how to sleep the Mayfly all the time and only wake up briefly whenever there’s a tip, record the tip, then go back to sleep.