Sending notification via AlarmManager and BroadcastReceiver does not work?

I'm scheduling a notification for 5 days ahead, so I create an alarm using the AlarmManager who fires a PendingIntent which triggers my BroadcastReceiver.

If I try the code for 10 seconds, it works. When I try it for 5 days, nothing happens.

The class NotificationScheduler is a helper class for setting and updating alarms.

The fire-dates are correct since I store them in a database, and I already proofed it.

Manifest:

<receiver android:name=".reminder.ReminderReceiver" />

NotificationScheduler:

class NotificationScheduler {

    companion object {

        const val NOTIFICATION_EXTRA_CLAIM_ID = "notification_extra_bookentry_id"

        const val INTENT_ACTION_REMINDER = "at.guger.moneybook.reminder"

        fun setReminder(context: Context, bookEntryId: Long, fireDate: Date? = null) {
            val mCalendar = Calendar.getInstance()

            val lFireDate = if (fireDate == null) {
                mCalendar.timeInMillis += 5 * 24 * 3600 * 1000
                mCalendar.set(Calendar.HOUR_OF_DAY, 12)

                mCalendar.time
            } else {
                fireDate
            }

            create(context, bookEntryId, lFireDate.time)

            AppDatabase.getInstance(context).reminderDao().insert(Reminder(bookEntryId, lFireDate))
        }

        fun updateReminder(context: Context, bookEntryId: Long) {
            cancel(context, bookEntryId)

            val mCalendar = Calendar.getInstance()
            mCalendar.timeInMillis += 5 * 24 * 3600 * 1000
            mCalendar.set(Calendar.HOUR_OF_DAY, 12)

            create(context, bookEntryId, mCalendar.timeInMillis)

            AppDatabase.getInstance(context).reminderDao().update(Reminder(bookEntryId, mCalendar.time))
        }

        fun cancelReminder(context: Context, bookEntryId: Long) {
            cancel(context, bookEntryId)

            AppDatabase.getInstance(context).reminderDao().delete(Reminder(bookEntryId))
        }

        private fun create(context: Context, bookEntryId: Long, fireDate: Long) {
            val mAlarmManager = context.getSystemService(Context.ALARM_SERVICE) as AlarmManager

            val mComponentName = ComponentName(context, ReminderReceiver::class.java)
            context.packageManager.setComponentEnabledSetting(mComponentName, PackageManager.COMPONENT_ENABLED_STATE_ENABLED, PackageManager.DONT_KILL_APP)

            val mIntent = Intent(context, ReminderReceiver::class.java)
            mIntent.action = INTENT_ACTION_REMINDER
            mIntent.putExtra(NOTIFICATION_EXTRA_CLAIM_ID, bookEntryId)

            val mPendingIntent = PendingIntent.getBroadcast(context, bookEntryId.toInt(), mIntent, PendingIntent.FLAG_UPDATE_CURRENT)

            if (Utils.isKitKat()) {
                mAlarmManager.setWindow(AlarmManager.RTC, fireDate, AlarmManager.INTERVAL_HOUR, mPendingIntent)
            } else {
                mAlarmManager.set(AlarmManager.RTC, fireDate, mPendingIntent)
            }
        }

        private fun cancel(context: Context, bookEntryId: Long) {
            val mAlarmManager: AlarmManager = context.getSystemService(Context.ALARM_SERVICE) as AlarmManager

            val mComponentName = ComponentName(context, ReminderReceiver::class.java)
            context.packageManager.setComponentEnabledSetting(mComponentName, PackageManager.COMPONENT_ENABLED_STATE_DISABLED, PackageManager.DONT_KILL_APP)

            val mIntent = Intent(context, ReminderReceiver::class.java)
            mIntent.putExtra(NOTIFICATION_EXTRA_CLAIM_ID, bookEntryId)

            val mPendingIntent = PendingIntent.getBroadcast(context, bookEntryId.toInt(), mIntent, PendingIntent.FLAG_UPDATE_CURRENT)

            mAlarmManager.cancel(mPendingIntent)
            mPendingIntent.cancel()
        }
    }
}

BroadcastReceiver:

class ReminderReceiver : BroadcastReceiver() {

    override fun onReceive(context: Context?, intent: Intent?) {
        if (context != null && intent != null) {
            when (intent.action) {
                NotificationScheduler.INTENT_ACTION_REMINDER -> {
                    val mPowerManager = context.getSystemService(Context.POWER_SERVICE) as PowerManager
                    val mWakeLock = mPowerManager.newWakeLock(PowerManager.PARTIAL_WAKE_LOCK, this::class.simpleName)

                    mWakeLock.acquire(WAKELOCK_TIME)

                    val iClaimEntryId = intent.getLongExtra(NotificationScheduler.NOTIFICATION_EXTRA_CLAIM_ID, -1)

                    showNotification(context, iClaimEntryId)
                    AppDatabase.getInstance(context).reminderDao().delete(Reminder(iClaimEntryId))

                    mWakeLock.release()
                }
            }
        }
    }

    private fun showNotification(context: Context, claimEntryId: Long) {
        val mNotificationManager: NotificationManager = context.getSystemService(Context.NOTIFICATION_SERVICE) as NotificationManager

        val nBuilder: Notification.Builder

        if (Utils.isOreo()) {
            val mNotificationChannel = NotificationChannel(NOTIFICATIONCHANNEL_CLAIMREMINDERID, context.getString(R.string.notificationchannel_claimreminder_title), NotificationManager.IMPORTANCE_DEFAULT)
            mNotificationChannel.description = context.getString(R.string.notificationchannel_claimreminder_description)

            mNotificationManager.createNotificationChannel(mNotificationChannel)

            nBuilder = Notification.Builder(context, NOTIFICATIONCHANNEL_CLAIMREMINDERID)
        } else {
            nBuilder = Notification.Builder(context)
        }

        val mClaimEntry: BookEntry = AppDatabase.getInstance(context).bookEntryDao().get(claimEntryId)

        val mCurrencyFormatter = DecimalFormat.getCurrencyInstance(Preferences.getInstance(context).currency.locale)

        nBuilder.setSmallIcon(R.drawable.ic_money)
        nBuilder.setContentTitle(context.getString(R.string.notification_claimreminder_title, mCurrencyFormatter.format(mClaimEntry.dValue)))
        val sContacts = mClaimEntry.getContacts(context).joinToString().takeIf { it.isNotEmpty() }
                ?: "-"
        nBuilder.setContentText(context.getString(R.string.notification_claimreminder_content, sContacts))
        nBuilder.setContentIntent(PendingIntent.getActivity(context, 0, Intent(context, MainActivity::class.java), PendingIntent.FLAG_UPDATE_CURRENT))
        nBuilder.setAutoCancel(true)

        mNotificationManager.notify(mClaimEntry.lId!!.toInt(), nBuilder.build())
    }

    companion object {
        const val NOTIFICATIONCHANNEL_CLAIMREMINDERID = "notification_channel_claimreminder"

        const val WAKELOCK_TIME: Long = 1000
    }
}

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