i solved the problem this morning.
i used a backup of " ManagmentService " and i replaced the actuel folder, hope for you that you did you backup.
you can find it : C:\ProgramData\QlikTech
before replace dont forget to stop all services.
when i activated all the services, I modified one triggers, after that, all the triggers came to normal automatiquely.
Thank you for the tip. I had indeed taken a backup of all the folders.
I had replaced the Management Service folder, and the QMC seemed to show all the triggers. But they failed to start at their schedule and I was unable to manually trigger them.
I then contacted Qliktech support who had a rather simple solution to this issue.
We just have to change the QMSChunkSize value from 100 to 20 in the config file of Management Service.
The file can be found in C:\Program Files\QlikView\Management Service\QVManagementService.exe.config
The issue was fixed after changing the value. Anyone else who are facing this problem can use this solution.