I'm building a number that should be able to include a decimal point for use in a calculation, where am I going wrong?

Question

I have made a function that should build the number for me, which was working and for some reason has stopped.

function buildNumber(num){
    console.log(num);
    if (calcState === true && currentNumber.toString().length < 9){
        if(currentNumber === 0){
            if (num === "."){
                currentNumber = Number(`${currentNumber}${num}`);
                console.log(currentNumber);
                checkDecimal = true;
                updateDisplay();
            } else if (num >=0 && num <= 9) {
                currentNumber = num;
                console.log(currentNumber);
                updateDisplay();
            }

        } else {
            if (num === "."){
                currentNumber = Number(`${currentNumber}${num}`);
                checkDecimal = true;
                console.log(currentNumber);
                updateDisplay();
            } else if (num >=0 && num <= 9) {
                currentNumber = Number(`${currentNumber}${num}`);
                console.log(currentNumber);
                updateDisplay();
            }
        }
    }
}

The event listener is triggered like so:

pointBtn.addEventListener("click", function(){
    console.log("Decimal pressed")
    if (checkDecimal === false){
        buildNumber(".");
    }
});

I'm just at a loss as to why it isn't triggering, the console.log just inside buildNumber() shows that the value is there when I click the button, it just doesn't do what I originally had it doing. Is there something glaringly obvious that I've missed?