The following post gave me the hint to make it work:
But not the actual accepted answer but rather:
[UIView animateWithDuration:1.0f delay:0.0f options:UIViewAnimationOptionLayoutSubviews animations:^{
[self.view layoutIfNeeded];
} completion:nil];
The optional parameter options:UIViewAnimationOptionLayoutSubviews
inspired me to try different options and the actual option needed was options:UIViewAnimationOptionBeginFromCurrentState
[UIView animateWithDuration:duration delay:delay options:UIViewAnimationOptionBeginFromCurrentState animations:^{
[self layoutIfNeeded];
} completion:nil];
Which allowed the animation to occur from the last position, even if constraints are removed and new ones are added.