I had the same problem. What helped me was adding validation for the answer. Sometimes, the solution wasn't correct with higher numbers in part two. I just did not count these invalid solutions.

bool isValid = clicksA * aX + clicksB * bX == prizeX && clicksA * aY + clicksB * bY == prizeY;

I had an issue with part two where I was pushing some buttons a negative amount of times to hit certain targets that shouldn't have been hittable...may or may not help you.  

I think that doesn't happen on the sample input but did happen on my actual input.

All unique solutions, even for part 2. Check that number of times A and B were pressed are not fractional, and lastly check if you correctly put braces in the equation for calculating presses.

// `consts`:
// a1: [0][0], b1: [1][0], c1: [2][0]
// a2: [0][1], b2: [1][1], c2: [2][1]
// part 2
// a_pressed = {b1*(c2 + CORRECTION) - b2*(c1 + CORRECTION)}/(a2*b1 - a1*b2)
a_pressed = (consts[1][0] * (consts[2][1] + CORRECTION as f64)
    - consts[1][1] * (consts[2][0] + CORRECTION as f64))
    / (consts[0][1] * consts[1][0] - consts[0][0] * consts[1][1]);

// b_pressed = {(c1 + CORRECTION) - a1*`a_pressed`}/b1
b_pressed = ((consts[2][0] + CORRECTION as f64) - consts[0][0] * a_pressed) / consts[1][0];

if a_pressed.fract() == 0.0 && b_pressed.fract() == 0.0 {
    tokens_2 += 3 * a_pressed as u64 + b_pressed as u64;
}