Why can't this laravel collection sort its index by time?

My objective is to optionally filter a list of attendances, sorting the employees by which of them comes the earliest or latest in a given period of time. My logic for going about this is:

• grouping attendance by each day
• rank each attendance by how early/late, depending on parameter, using their index on the sorted list
• sum their indexes to find the highest value in each case

The problem now is that, the same attendances always carry same index, irrespective of sorting algorithm used ie earliest always carries 0. Sorting the list simply pushes the element to the bottom of the list visually, but it still bears 0, which makes no sense

The code I originally had was

protected function punctualChart ($attendanceCollection, ?string $puncMode) {

        $puncMode = $puncMode?? "ear";
// group them into each day. rank by employee with most days
        $attendanceDays = $attendanceCollection->groupBy(function ($attendance) {

            return $attendance->created_at->format("m-d");
        })
        ->map(function ($daysCollection) use ($puncMode) { // then sum their value for each day? add their indexes. depending on the mode, we know whether highest or lowest is the winner

            return $daysCollection->sort(function ($a, $b) use ($puncMode) {

                $date1 = $a->created_at;

                $date2 = $b->created_at;

                if ($puncMode == "lat") {

                    if ($b > $a) return 1;

                    if ($a > $b) return -1;

                    return 0;
                }
                else {

                    if ($a > $b) return 1;

                    if ($b > $a) return -1;

                    return 0;
                }
            });
        })->values();
// dd($attendanceDays->get(1), $attendanceDays->get(2), $puncMode);
        $scoreEmployee = [];

        foreach ($attendanceDays as $attendanceCollection) {

            foreach ($attendanceCollection as $index => $attendance) {
dump($index);
                $employeeId = /*$attendance->employee->last_name.*/$attendance->employee_id;

                if (!array_key_exists($employeeId, $scoreEmployee))

                    $scoreEmployee[$employeeId] = /*0;*/[

                        "value" => 0,

                        "model" => $attendance->employee->last_name
                    ];

                $scoreEmployee[$employeeId]["value"] += $index+1; // offset 0-based index
            }
        }

        $sortedEmployeeScores = IlluminateSupportArr::sort($scoreEmployee, "value");
dd($scoreEmployee, $sortedEmployeeScores);
        return $scoreEmployee;
    }

It was subsequently simplified to

protected function punctualChart ($attendanceCollection, ?string $puncMode) {

        $puncMode = $puncMode?? "ear";
// group them into each day. rank by employee with most days
        $attendanceDays = $attendanceCollection->groupBy(function ($attendance) {

            return $attendance->created_at->format("m-d");
        })
        ->map(function ($daysCollection) use ($puncMode) { // then sum their value for each day? add their indexes. depending on the mode, we know whether highest or lowest is the winner

            return $puncMode == "ear"? $daysCollection->sortBy("created_at"):

            $daysCollection->sortByDesc("created_at");
        })/*->values()*/;
// dd($attendanceDays->get(1), $attendanceDays->get(2), $puncMode);
        $scoreEmployee = [];

        foreach ($attendanceDays as $attendanceCollection) {

            foreach ($attendanceCollection as $index => $attendance) {
dump($index);
                $employeeId = /*$attendance->employee->last_name.*/$attendance->employee_id;

                if (!array_key_exists($employeeId, $scoreEmployee))

                    $scoreEmployee[$employeeId] = /*0;*/[

                        "value" => 0,

                        "model" => $attendance->employee->last_name
                    ];

                $scoreEmployee[$employeeId]["value"] += $index+1; // offset 0-based index
            }
        }

        $sortedEmployeeScores = IlluminateSupportArr::sort($scoreEmployee, "value");
dd($scoreEmployee, $sortedEmployeeScores);
        return $scoreEmployee;
    }

From where I realised the sorting is unnecessary. Funny enough, the results are auto sorted. However, that indexing is fixed and unable to be altered. Whatever the case may be, same elements always have same indexes. So I thought maybe, reversing the list would help ie instead of passing puncMode, I’ll just reverse the array to obtain the inverse. But that doesn’t work either

So what am I doing wrong and how do I swap their indexes to reflect their position? Then sum this position for rendering on my chart (you don’t need to add this part. Just revealing for the sake of completion)?