If you apply forces in Tick or some other function, this typically occurs outside the physics step.
In some cases you can get more accurate application of forces if you do it during the actual physics step.
Using AddCustomPhysics
The BodyInstance on PrimitiveComponents has a delegate for adding custom physics during tick. This is one way to run logic during the physics step.
FCalculateCustomPhysics Calculate;
Calculate.BindLambda([this](float DeltaTime, FBodyInstance* BodyInstance)
{
BodyInstance->AddForceAtPosition(SomeForce, BodyInstance->GetCOMPosition());
});
Primitive->GetBodyInstance()->AddCustomPhysics(Calculate);
If you want to keep applying the custom physics on every frame, AddCustomPhysics must be called on tick.
(There are probably some other ways of doing this as well)