This is most evident in iOS. I've set up a demo app:
https://stackblitz.com/edit/nativescript-stackblitz-templates-vwcmqt
In iOS, if you follow the steps (they're numbered) you'll see that when you navigate back on step five, the animation runs twice—backwards then forwards. This appears to come from the shouldDetach method NSRouteReuseStrategy. If I use the previous code for shouldDetatch that was altered here:
bebcde2
then it works without problem.
NOTE: For this demo, I've used 14.2.6-alpha.0 because without it, I can't use modals with ModalDialogParams because of injector scope issues. However, this router problem described above also occurs in 14.2.5 when the modal corrections are in place. Either way, something isn't working as it should.