I have faced the issue in pega Upgrade(7.x To 8.4 Version). Activity has one step(Call SetTicket) and this Activity fire when the Goal Passed in the SLA. But this Activity is not fired . Then I have Removed SetTicket Step and added property-Set.After that this Activity is working fine. When i was added Set Ticket to Step then SLA not fire that Activity. Could you please help me to sort this out.
Conceptually, you have to remember that the set ticket will only succeed if the case being updated is not locked - Normally this means all active flows have reached an 'assignment' (unless you have been naughty and explicitly put a commit in an activity mid-flow).
If the case cannot be suitably locked, the set ticket command executes but then rolls-back when save/commit is performed... On roll-back there is no evidence it ever executed! The best way to check if this is happening is by adding some logging (Log-Message) to the activity in the flow that is being resumed by your ticket.