nodejs - async.each function with async operation on each iteration

I have a question about async.each behavior. consider the code:

const examples = [1,2];

const asyncTask = (index) => {
    return new Promise(resolve => {
        setTimeout(() => {
            console.log(`Inside setTimeout-${index}`);
            resolve(true);
        }, 1500)
    });
}

function testingAsyncEach(callback){
    async.each(examples, (example, innerCallback) => {
        asyncTask(example).then(isDone => {
            console.log(`isDone: ${isDone}`);
            innerCallback(null);
        });
    }, err => {
        console.log('done testingAsyncEach');
        return callback()
    })
}

testingAsyncEach(() => {console.log('final callback testingAsyncEach');})

a simple code using the "async" module in nodejs, using the array [1,2] and on each item in the array executing the function "asyncTask" which returns a new promise which gets resolve after a timeout of 1.5 seconds.

in this scenario the output of the program is:

Inside setTimeout-1
isDone: true
Inside setTimeout-2
isDone: true
done testingAsyncEach
final callback testingAsyncEach

but when I changed the "testingAsyncEach" function to use the "await" syntax:

function testingAsyncEach(callback){
    async.each(examples, async (example, innerCallback) => {
        const isDone = await asyncTask(example);
        console.log(`isDone: ${isDone}`);
        innerCallback(null);
    }, err => {
        console.log('done testingAsyncEach');
        return callback()
    })
}

the async.each is not waiting for the "asyncTask" to end. output:

Inside setTimeout-1
isDone: true
done testingAsyncEach
final callback testingAsyncEach 
Inside setTimeout-2
isDone: true

Can you please help me understand why using the "await" instead of the "then" change the behavior? how can I still use the "await" syntax and get the proper output? Thanks!