Locked Task : unlockmembers crash

I get a notification in panel admin. 

I click on it and it result by a bug.

ValueError: max(): Argument #1 ($value) must contain at least one element (0)
#0 /home/damien_prod/Internazionaleprod/public_html/applications/core/tasks/unlockmembers.php(64): max()
#1 /home/damien_prod/Internazionaleprod/public_html/system/Task/Task.php(336): IPS\core\tasks\unlockmembers->execute()
#2 /home/damien_prod/Internazionaleprod/public_html/applications/core/modules/admin/settings/advanced.php(756): IPS\Task->run()
#3 /home/damien_prod/Internazionaleprod/public_html/system/Dispatcher/Controller.php(128): IPS\core\modules\admin\settings\advanced->runTask()
#4 /home/damien_prod/Internazionaleprod/public_html/applications/core/modules/admin/settings/advanced.php(98): IPS\Dispatcher\Controller->execute()
#5 /home/damien_prod/Internazionaleprod/public_html/system/Dispatcher/Dispatcher.php(169): IPS\core\modules\admin\settings\advanced->execute()
#6 /home/damien_prod/Internazionaleprod/public_html/admin/index.php(15): IPS\Dispatcher->run()
#7 {main}