Go to the task you want to assign and click on the "+" Icon in the Assignees section.

Select the Groups and Contributors you want to assign the task to then click Save.

Go to the task you want to assign and click on the "Team" Icon at the bottom of your screen.

Go to Assignees and check the boxes next to the names of the people and groups you want to add.

You can set up the groups in the team section.

Click on the icon at the bottom of your screen to validate.

Go to the task you want to assign

Click on "Assign to"

Select the names of the people and groups you want to add, Then click "Done"

You can set up the groups in the team section.

The Task is now assigned to the right contributors and groups.