Listener not responsive on iOS port

Question

I'm porting my Android game written with the libGDX engine to iOS using RoboVM. The game works fine but all the ImageButton and TextButton do not respond to touch inputs every time they are touched. The buttons respond sometimes but it is only after a couple of touches and sometimes the wrong button is pressed.

I have attempted to change:

button1.addListener(new ChangeListener() {
        public void changed (ChangeEvent event, Actor actor) {...}});

to:

button1.addListener(new ClickListener(){
        @Override public void clicked(InputEvent event, float x, float y) {...}});

but there is no change in button performance.

The buttons are very responsive on the Android version of the game. Does anyone have any information as to why Listeners are not very responsive on libGDX iOS ports?

I have noticed that as I increase the size of TextButtons and ImageButtons, they become more reliable. Not sure why this is the case. I am currently implementing a temporary fix by making all the buttons larger, but this is not ideal.