hasManyThrough not working as expected inside foreach loop

Question

I have 'hasManyThrough' relationship in model 'Customer' as shown below:

public function Assignments()
{
    return $this->hasManyThrough(Assignment::class, Contract::class, 'customer_id', 'contract_id', 'customerId', 'contractId');
}

I'm using it like this:

if (is_array($customer)) {
    foreach ($customer as $cus) {
        $completedDosesNum += $cus->Assignments()
            ->whereDate('end_date', '<', $now)
            ->count();
        $inProgDosesNum += $cus->Assignments()
            ->whereDate('start_date', '<=', $now)
            ->whereDate('end_date', '>=', $now)
            ->count();
        $expBadges += $cus->Contracts()
            ->whereDate('end_validation_date', '<', $now)
            ->count();

        // Assignments of Expired Contracts
        $contractsEx = $cus->Contracts()
            ->whereDate('end_validation_date', '<', $now)
            ->get();
        // Assignments of Alive Contracts
        $contractsAl = $cus->Contracts()
            ->whereDate('end_validation_date', '>=', $now)
            ->whereDate('notification_date', '<=', $now)
            ->get();

        $assignments = $cus->Assignments()->get();
        foreach ($assignments as $assign) {
            $over007D3M += $assign->AssignmentDetails()
                ->where([
                    ['hp007_dose_result', '>=', $doseConf->min007]
                ])
                ->whereDate('date_dose_result', '>=', $now->subMonths(3))
                ->count();
            $over10D3M += $assign->AssignmentDetails()
                ->where([
                    ['hp10_dose_result', '>=', $doseConf->min10]
                ])
                ->whereDate('date_dose_result', '>=', $now->subMonths(3))
                ->count();
            $over007D6M += $assign->AssignmentDetails()
                ->where([
                    ['hp007_dose_result', '>=', $doseConf->min007]
                ])
                ->whereDate('date_dose_result', '>=', $now->subMonths(6))
                ->count();
            $over10D6M += $assign->AssignmentDetails()
                ->where([
                    ['hp10_dose_result', '>=', $doseConf->min10]
                ])
                ->whereDate('date_dose_result', '>=', $now->subMonths(6))
                ->count();
            $over007D9M += $assign->AssignmentDetails()
                ->where([
                    ['hp007_dose_result', '>=', $doseConf->min007]
                ])
                ->whereDate('date_dose_result', '>=', $now->subMonths(9))
                ->count();
            $over10D9M += $assign->AssignmentDetails()
                ->where([
                    ['hp10_dose_result', '>=', $doseConf->min10]
                ])
                ->whereDate('date_dose_result', '>=', $now->subMonths(9))
                ->count();
            $over007D12M += $assign->AssignmentDetails()
                ->where([
                    ['hp007_dose_result', '>=', $doseConf->min007]
                ])
                ->whereDate('date_dose_result', '>=', $now->subMonths(12))
                ->count();
            $over10D12M += $assign->AssignmentDetails()
                ->where([
                    ['hp10_dose_result', '>=', $doseConf->min10]
                ])
                ->whereDate('date_dose_result', '>=', $now->subMonths(12))
                ->count();
        }

        foreach ($contractsEx as $value) {
            $uWorkers += $value->AssignmentDetails()->count();
        }
        foreach ($contractsAl as $value) {
            $mWorkers += $value->AssignmentDetails()->count();
        }
        dump($inProgDosesNum);
    }
} else {
    $completedDosesNum = $customer->Assignments()
        ->whereDate('end_date', '<', $now)
        ->count();
    $inProgDosesNum = $customer->Assignments()
        ->whereDate('start_date', '<=', $now)
        ->whereDate('end_date', '>=', $now)
        ->count();
    $expBadges = $customer->Contracts()
        ->whereDate('end_validation_date', '<', $now)
        ->count();
    // Assignments of Expired Contracts
    $contractsEx = $customer->Contracts()
        ->whereDate('end_validation_date', '<', $now)
        ->get();
    // Assignments of Alive Contracts
    $contractsAl = $customer->Contracts()
        ->whereDate('end_validation_date', '>=', $now)
        ->whereDate('notification_date', '<=', $now)
        ->get();

    $assignments = $customer->Assignments()->get();
    foreach ($assignments as $assign) {
        $over007D3M += $assign->AssignmentDetails()
            ->where([
                ['hp007_dose_result', '>=', $doseConf->min007]
            ])
            ->whereDate('date_dose_result', '>=', $now->subMonths(3))
            ->count();
        $over10D3M += $assign->AssignmentDetails()
            ->where([
                ['hp10_dose_result', '>=', $doseConf->min10]
            ])
            ->whereDate('date_dose_result', '>=', $now->subMonths(3))
            ->count();
        $over007D6M += $assign->AssignmentDetails()
            ->where([
                ['hp007_dose_result', '>=', $doseConf->min007]
            ])
            ->whereDate('date_dose_result', '>=', $now->subMonths(6))
            ->count();
        $over10D6M += $assign->AssignmentDetails()
            ->where([
                ['hp10_dose_result', '>=', $doseConf->min10]
            ])
            ->whereDate('date_dose_result', '>=', $now->subMonths(6))
            ->count();
        $over007D9M += $assign->AssignmentDetails()
            ->where([
                ['hp007_dose_result', '>=', $doseConf->min007]
            ])
            ->whereDate('date_dose_result', '>=', $now->subMonths(9))
            ->count();
        $over10D9M += $assign->AssignmentDetails()
            ->where([
                ['hp10_dose_result', '>=', $doseConf->min10]
            ])
            ->whereDate('date_dose_result', '>=', $now->subMonths(9))
            ->count();
        $over007D12M += $assign->AssignmentDetails()
            ->where([
                ['hp007_dose_result', '>=', $doseConf->min007]
            ])
            ->whereDate('date_dose_result', '>=', $now->subMonths(12))
            ->count();
        $over10D12M += $assign->AssignmentDetails()
            ->where([
                ['hp10_dose_result', '>=', $doseConf->min10]
            ])
            ->whereDate('date_dose_result', '>=', $now->subMonths(12))
            ->count();
    }

    foreach ($contractsEx as $value) {
        $uWorkers += $value->AssignmentDetails()->count();
    }
    foreach ($contractsAl as $value) {
        $mWorkers += $value->AssignmentDetails()->count();
    }
}

in the first block of 'if', the 'Assignments()' method not working as expected and the variable '$completedDosesNum' contains the count of the first item of the loop!!?

but in the second block it works fine and gives me the correct count of 'Assignments()' for the selected customer.

Thanks in advance.