Simple problem, but I have no debug skills at the moment. Just needed to change the open angle = 0.f and that fixed it. However I notice in your own Github file (https://github.com/UnrealCourse/03_BuildingEscape/commit/b74a2161bfdfb7875273de0be892f28330415c3a) that somehow you are leaving the OpenAngle = 90.f and somehow it is still working, that is what threw me.
Your OpenAngle actually is your closed angle, then it opens -60 or -80 as I have it, so mine is closed at 0.f, then the rotator is triggered and it opens -80.f, but yours is closed at 90.f
OpensDoor.h…
…private:
UPROPERTY(VisibleAnywhere)
float OpenAngle = 0.f;
UPROPERTY(EditAnywhere)
ATriggerVolume* PressurePlate;
UPROPERTY(EditAnywhere)
AActor* ActorThatOpens;