Customer can tick off (complete) a task in project preview window on frontend

Hi,

I’ve just bought Zephyr Project Manager pro for my B2B site and thought this is a great plugin.

I’ve notice a few behaviors though, so am gonna list them one in each different post.

Background:

The B2B website provides customers with custom product sourcing service. Assuming Mark is a registered customer, Jessie is Mark’s account manager. I’m the WP admin.
Jessie is currently handling a sourcing project for Mark, which involves manufacturer screening, prototyping, test & approval, sample production, and mass production, etc.
We’ve created a ZPM project on WP backend, so that Mark can track the progress on the frontend. So everyone is on the same page.
As for roles, Jessie and I are ZPM_Manager, and Mark is a ZPM_User and can only access frontend.
Jessie creates the project and a few tasks on the backend. I enabled Jessie and Mark as project members. I also created a team consisting of Jessie and Mark. When Jessie creates the tasks, she assigns it to the team.
For this setup, both the project and the tasks are visible to Mark on the frontend.
Jessie wants Mark to be able to view the progress and make comments on frontend, but not change the state of anything.

The behavior noticed was:

When Mark clicks on the project, a preview “window” slides in displaying the tasks, among other things. He can actually tick off a task making it “completed”.

So is there any way to prevent Mark from ticking off tasks? Are we missing any step when setting up the project and role permission?

Thanks.