Can't manage to delete a project

Hi,
I'm currently having an issue while trying to delete a project.
I moved all the tickets and activitys to another project and there's no remaining things (tickets, activitys ...), but somehow it keeps telling me that I can't delete it because there's a work allocated to this project (see the screenshot)

Thank you in advance,
Regards

Thank you for the reply,
I tried the Admin consistency repair tool,
It detected some errors and claimed that it corrected them.
But the errors concerning work keep coming back everytime i use the error scan and continue to say it's corrected.
(Screenshot attached)

Regards

So, I tried to update an activity of the project, didn't change the problem.
I'm not sure that the consistency errors are related to this problem.
In fact, I am working on a test environment, so I restored my db from a backup I did just before I moved the demands and activitys (in order to delete the projects).
I used the check error admin tool, errors were there before and aren't resolving neither.

I am currently not totally getting the meaning of "work" in my error message, like, what can it be if I moved all the demands, activitys, flags ect from the project ?

Regards

EDIT : Or maybe you could try to explain me wich reference it represents in the db ? Idk