I created two new differential pairs in PCB Editor, Constraint Manager. After importing a new Capture netlist, however, the Diff Pairs are now gone.
If you don’t create the diff pairs in the schematic and update them to the PCB Design using the Import Netlist controls, they are deleted in the PCB Design when a new netlist is imported. This is true for all PCB Versions.
You can access the PCB Editor, Import Logic/Netlist dialog from the Import > Netlist menu.