all content in the first column trying to use mat-expansion-panel in a table

Question

I tried to use the mat-expansion-panel in the table but when I put this feature before my tr, all the content is in the first column. I don't understand why...

I tried to use cdkAccordion but still the same problem.

You will find an example with mat-expansion-panel below :

https://stackblitz.com/edit/angular-6r3afm?file=src/app/cdk-accordion-overview-example.html