User "Last active" information is not accurate

Summary
The "Last active" feature in the user profile is not being displayed with accuracy, some users have their last activity shown as "Not active in the last 180 days", while other users who are also inactive for more than 180 have their last activity shown as "17 Aug 2017".

Steps to reproduce
1. Navigate to the User Management
2. Open the profile of a user that has not been active for a while
3. Check the user "Last active" information

Expected Results
If the user has not been active in the last 180 days, it should be displayed as "Not active in the last 180 days"

Actual Results
The actual last active date is displayed. E.g: 17 Aug 2017