Bug : ionic v4 ranger ionBlur Event not work correctly

i use ionic Ranger for music time bar and use ionBlur on ion-range for update music current time , in ionic 3 its work correctly but in new version it’s not Emitted

ionChange work good but ionBlur not fired

I have the same problem with ionic 4.0.2

1/ ionBlur event has never fired
2/ ionFocus event will only fire once.
3/ ionChange event is ok.
4/ ionic 3.9.2 is working fine.

Any solution?

(touchend)=“myfunction()” it works