This is the solution I found, i had the loop stop at +2 away from the current index instead of a maxX/maxY, and saved the sums of all the hourglasses in an array which was a unnesscary decision after looking at your code, my variable names are also very long which i think i should change, everyone else seems to use very short variables.

function hourglassSum(arr) {
        let top, mid, bottom = 0
        //looking back idk why i thought these were pyramids!!!
        let pyramid = [] 
        let innerPyramid= []

        function inOrder(a,b) {
                return a - b
        }

        // outer loop moves up and down
        for (const [index, value] of arr.entries()) {
                if(index+2 < arr.length){
                        //inner loop goes left to right
                        for(const [innerIndex, innerValue] of value.entries()){
                                if(innerIndex + 2 < value.length){
                                        //get the sum of the top 
                                        top = innerValue + value[innerIndex+1] + value[innerIndex+2]
                                        //get the sum of the mid
                                        mid = arr[index+1][innerIndex+1]
                                        //get the sum of the bottom
                                        bottom = arr[index+2][innerIndex]+arr[index+2][innerIndex+1]+arr[index+2][innerIndex+2]
                                        //get the sum of the entire hourglass
                                        innerPyramid[innerIndex] = top+mid+bottom
                                }else{
                                        break
                                }
                        }
                        //combine the two arrays
                        Array.prototype.push.apply(pyramid, innerPyramid)
                }else{
                        break
                }
        }
        return pyramid.sort(inOrder)[pyramid.length - 1]
}