Begin of the insertion### Steps to reproduceEnd of the insertion Begin of the deletion End of the deletion

Begin of the insertion1. Login as a user

2. Go to the activity tab in a work package in a project (eg. Stream Mobile App)

3. Add a comment and use @ to check for a mention

4. Check that the list of users to mention


### What is the buggy behavior?

* All the users that are part of that instance are available for mentioning


### What is the expected behavior?

* Only the members of the project should appear as possible mentions inside of that project.


**Operating System**

* [ ] Windows
* [ ] Mac OS X
* [x] Mobile iOS
* [x] Mobile Android
* [ ] Linux (please specify distro)
* [ ] Chrome OS
* [ ] Other (please specify)End of the insertion