Hello.
I tried to import a list of tasks with the CSV Importer. Anytime Reporter or Assignee is sourced, the task creation fails.
I used the form first_name.lastname but I also tried with ID number and mail adress. Each time Reporter or Assignee is not empty, the import fails.
Even when R or A is... the Project Lead.
For a brief history, one of my teammates succeeded in importing these on 27th of June 2019. She tried today : same errors as me.
On the screenshot, you can see the error message when I tried to import with the form first_name.lastname .
Can somebody help us solving this mystery ?

Thanks,
TTVD