Are you able to manually select the SLA from the response level attribute. And do you see the escalation points being generated when you hit the activation status?
Yes the Change SLA has always been selected in the response level attribute:
I have created a new change with the priority set to high, below is the view from the change form. It looks like it is picking up the escalations but not the breach time:
This is the calculation set on the process breach time attribute:
Yep, you need to set a breach flag at 100%. This should then set the breach time. Because you just have a 50% and I'm assuming no breach flag on that, that is why the breach flag is not being set.
Give that a go and let us know. You might need to restart background services for that to take effect.