Cloud Functions bucket.upload() is not running at all - firebase

Question

here is what I am trying to do using Firebase:
create a backup file from realtime database
upload to firebase storage
do this every morning
but I am having problem on number 2; after the log of back up file creation success, no other log appears, not even a failed message.
no log after file creation
Even worse is that it sometimes works, which makes me doubtful about the consistency of the functionality.
my code:
var promiseFileCreation = function(fileName, jsonBackup){
console.log("promiseFileCreation starting");
return new Promise(function (resolve, reject){
fs.writeFile('/tmp/'+fileName, jsonBackup, function(fs_err){
if(!fs_err){
resolve("File "+fileName+" creation success");
} else {
reject("File "+fileName+" creation failure: "+fs_err);
}
})
}).catch(function(error){
reject("FileCreation Error");
})
}
var promiseBucketUpload = function(fileName, fileDest){
console.log("promiseBucketUpload starting")
return new Promise(function (resolve, reject){
console.log("promiseBucketUpload promise starting")
bucket.upload('/tmp/'+fileName, { destination: fileDest }, function(upload_err){
if(!upload_err){
resolve("File "+fileName+" upload to "+fileDest+" success");
} else {
reject("File "+fileName+" upload to "+fileDest+" failure: "+upload_err);
}
})
}).catch(function(error){
reject("BucketUpload Error: "+error);
})
}
Promise.all([promiseText, promiseDate, promiseTitle, promiseLikedCount, promiseViewCount, promiseComments]).then(function (values){
var jsonPostObj = {
post: [],
counter: []
}
jsonPostObj.post.push({
date: values[1],
text: values[0],
title: values[2]
})
jsonPostObj.counter.push({
likedCount: values[3],
viewCount: values[4]
})
var jsonCommentsObj = JSON.parse(values[5]);
const jsonArchiveObj = {...jsonPostObj, ...jsonCommentsObj}
var jsonArchive = JSON.stringify(jsonArchiveObj);
const yesterday = getYesterdayDateFull();
var fileName = "archive_"+yesterday;
var fileDest = "history/"+yesterday.substring(0,4)+"/"+yesterday.substring(4,6)+"/"+fileName;
console.log("Archive file name: "+fileName);
console.log("Archive destination: "+fileDest);
promiseFileCreation(fileName, jsonArchive).then(function(resultSuccessFs){
console.log(resultSuccessFs);
// BUCKETUPLOAD here
promiseBucketUpload(fileName, fileDest).then(function(resultSuccessBucket){
console.log(resultSuccessBucket);
return promiseBackupResult(true);
}, function(resultFailureBucket){
console.log(resultFailureBucket);
return promiseBucketResult(false);
})
}, function(resultFailureFs){
console.log(resultFailureFs);
return promiseBackupResult(false);
});
}).catch(function(errPromiseAll){
console.log("Promise.all error: "+errPromiseAll);
return promiseBackupResult(false);
})
}
I removed unnecessary codes, like other promises. The file creation seems to work fine.
Does anyone see why bucket.upload() is not called at all? Thanks in advance.