According to what I know, it is used in conjunction with the "Resolve roles/groups to users" option.

In a nutshell, the server maintains a list of users assigned as a destination user.  When synchronizing, it will again resolve the role/groups to users and compare it to the original list of users and see what changes are made (i.e. instances/rights/slots to add/remove).

This option does not impact anything if you create a slot per role as there is there is no additional slots to speak of.

Is it a bug in the UI to have "Keep roles synchronized" box enabled when "Create a slot for each role and group" is selected?

This behavior is in 4.6.7.

Hi PeterYao,

If by enabled you mean that it is an available option to click (or not greyed out), I think that this is an expected behavior just by looking at this documentation: http://help.k2.com/onlinehelp/k2blackpearl/userguide/4.6.7/webframe.html#destination_rule-destination_rule_options_scontinued].html#tracksearch=keep roles synchronized

If I'm understanding this incorrectly, please let me know so I or someone else can better answer you. Thanks!

"Keep roles synchronized" option comes into play only when you select "Resolve all roles and groups to users" option. When you not reolving roles to users single slot is being created for them and all members of the group can access slot. Role membership is being updated automatically every 10 minutes by default.

As soon as you select  "Resolve all roles and groups to users" role will be resolved into users and respective number of slots will be created based on current state of the role, this means that users added in last 10 minutes won't get any slots as role was not refreshed yet to reflect their membership.

To address this/get changes to the K2 role reflected you can use the "Keep roles synchronized" checkbox which will keep them in sync on interval. As per K2 documentation:

"When the Keep roles synchronized check box is selected, the server will automatically synchronize roles when users are added and/or removed. The Activity Instance will react, by adjusting the slots (if slot per destination is selected), Create new or Expire Activity Instance Destinations (if the plan option is Plan per destination). In the case of Plan Just Once, only the slots will be adjusted to keep the Succeeding Rule in sync (All Slots=Completed)."

For huge roles which frequently have large scale changes in their membership Keep roles synchronized setting may have performance costs.