Something at this level will be hard to get answers through the community.
I suggest filing an Service Request on SupportNet so you can be provided with the additional support needed.
Thanks , Vern Wnek
Being in Customer Support my first response would be to understand what has happened. My guess is the differential pairs have been pushed from one layer to another or the stackup has changed. You can start to push and shove the diff pair around and see if it starts to behave properly again.
If you need more help to figure this out open up a Service Request and provide a test case.
Do you have the High Speed Design Option (HSR) enabled? (or using pinnacle which automatically recieves an HSR license)
Setup > Licensed Modules > High Speed (HSR).
The design which I have the problem says that HSR is not available.
But when I start a new design differential lines can be be routed. In those I can not find Setup > Licensed Modules > High Speed (HSR).