Android main(UI) thread freezing when running many Runnables on singleThreadExecutor

Question

I am creating an Idle fighting game through Android Studio Java which requires running a lot of attacking/general combat animations in sequence. I am using ExecutorService instantiated through SingleThreadExecutor to execute Runnables containing animation code.

Example code excerpt:

//list of animations to run.
LinkedList<Runnable> animationTasks = new LinkedList<>();

//example add an animation to the list.
animationTasks.add(animateMissOnTarget(target);

//how the animations are executed in sequence.
ExecutorService executor = newSingleThreadExecutor();
for (Runnable animation : animationTasks) {
    executor.execute(animation);
}


//example animation runnable.
private Runnable animateMissOnTarget(String target) {
    return new Runnable() {
        @Override
        public void run() {
            View targetCombatantView = combatantViewLookup.get(target);

            ImageView missImageView = targetCombatantView.findViewById(R.id.combatant_miss_image);

            missImageView.post(()-> {
                missImageView.setVisibility(View.VISIBLE);
                ((AnimationDrawable) missImageView.getBackground()).start();
            });

            try {
                sleep(combatSpeed);
            } catch (InterruptedException e) {
                e.printStackTrace();
                findViewById(R.id.interrupted).setVisibility(View.VISIBLE);
            }

            missImageView.post(()-> {
                missImageView.setVisibility(View.INVISIBLE);
                ((AnimationDrawable) missImageView.getBackground()).stop();
            });
        }
    };
}

Sometimes (although rarely) the phone's entire main (UI) thread freezes and stops responding which is a pretty big bug for a game to have.

Unsure if I've done this in a very silly way. Does anyone know if there's a better way through Android to display lots of animations in a row rather than the method I am going with?

Thanks all :)

I have rewritten the code multiple times to reduce dynamic loading of drawables and such which has reduced the frequency of the bug, however it still persists so I am wondering if it is something more core to Android OS, like the OS killing off threads to save CPU etc