After iOS 8 UIView animation does not work. If something other has changed on the screen, UIView position is reseted.

I have an old application which has an UIView, a mercury. Whenever a negative or positive vote happens, it should change its state on a benchmark from 0-100, showing the current vote standing. The problem is when I change something else on the screen, for example a text in a label, the position of the mercury is reseted to its original position (which is determined in the .xib file).

It worked perfectly in iOS 7.

@property(nonatomic) IBOutlet UIView *mercury;

-(IBAction)happyBtn:(id)sender
{
    self.counter++;
    self.positiveVotes++;
    if(self.show!=NO){
        [self newPosition:YES];
    }else{
        [self newPosition:NO];

    }

}

-(IBAction)peekBtn:(id)sender
    {
        if(self.peekCounter!=0){
            self.peekCounter--;
// * if I comment this out, the mercury's position is reseted
            //[self.peekLabel setText:[NSString stringWithFormat:@"Available peeks: %d",self.peekCounter ]];
            [self newPosition:YES];
        }else{
            UIAlertView *alertV = [[UIAlertView alloc] initWithTitle:@"No more peeks" message:@"No more peeks available" delegate:nil cancelButtonTitle:@"OK" otherButtonTitles:nil];
            [alertV show];
        }
    }

 -(void)newPosition:(BOOL)show
{

        CGFloat mod = 100/self.counter;
        self.pos = mod *self.positiveVotes;
        self.fpos = 400- ((300/100)*self.pos);
        NSLog(@"counter:%f, positive:%f, mod:%f pos:%f, fpos:%f",self.counter,self.positiveVotes,mod,self.pos,self.fpos);
        CGRect mercurybox = self.mercury.frame;
        mercurybox.origin.y = self.fpos;


        if(show==YES){

            self.mercury.frame = mercurybox;
            //self.tipLabel.text = [NSString stringWithFormat:@"%0.1f",self.pos];

        }

}