No activities are linked to Last Modified date

Document ID : KB000121614
Last Modified Date : 28/11/2018
Show Technical Document Details
For Service Desk/CMDB, for every ticket, there is a last modified date and many users expect this exact date should be logged in ticket activity log. However, this is not always the case and they may wonder why. This tech doc explains why this happens.
Why for some tickets their last modified activity do not show up in ticket activity log? . For example, as of 11/27/18 12:20 PM, CH438062 was showing last modified date of 11/23/2018 01:07 pm. However, the last activity was dated 10/29/2018 11:03 am. 
Service Desk/CMDB 12.9, 14.1, 17.1 on windows/linux/unix
The reason is for some ticket activities, the "log me" flag is not checked. For example, for change order status change, if the "Status" activity association
does not have "Log me" checkbox checked then for change order tickets, the status change activities will not be logged in activity log but last modified date will change and as a result, if you look at change order activity log, you will not see any activity show up for status change.