iPhone 4S (iOS 7.1) - iCloud Contacts/Calendars dissappearing

Hey guys,

I was wondering if you guys had this same problem. I searched around Google and in this community, and it seems like you guys also do. I'm going to create a new thread with more details below..

Basic Info:

• iPhone 4S (Chinse (CN) phone)
• iOS 7.1
• I'm an American working in Shanghai, China.

Issue:

• At random times and at least 3 times a month, my contacts and calendar events would dissappear.
• When it disappears, ...
  • I see only phone numbers in the Phone application and when someone calls me.
  • My Contacts app only list like 5 out of my 230+ contacts, I dont' know why only these 5 were not affected. This is my iCloud contacts.
  • My Calendar is empty and no longer shows which Calendar I can hide or show. I had 3 different calendars (iCloud, Personal, and Work calendars)
• After about 2 hours (or even longer), the Contacts and Calendars will slowly return as it tries to download from the iCloud server (I can see the loading animation in Calendar and the contacts slowly showing up). Sometimes it doesn't return after 2 hours and I have to manually force it by turning OFF and ON the calendars sync.

Already tried:

• Restarting the phone (soft shutdown and hard shutdown by Home + Power)
• Already checked to make sure iCloud, Contacts, and Calendars is ON in Settings
• Already tried turning them OFF, wait about 10 minutes, then turn it back on. Sometimes it loads back the data, sometimes it doesn't. Right now, I have my work calendar missing.
• This bug happens seem to happen only when I'm on Wi-fi. Didn't see it happen on 3G yet. Not sure, but it seems to happen when I switch from 3G to Wifi automatically when I got home. Need to confirm this.
• Tried syncing to iCloud to see if it comes back, 1/3 of the time it would.

History w/ this bug:

• I had this phone since iOS 6.
• This bug first appeared in iOS 7, which also happened at least 3 times a month. I reported this directly to Apple Support, but not sure if they read it.
• In iOS 7.0.x, this bug stopped reappearing. Seems like they heard us and fixed it. I never had this issue again.
• In iOS 7.1, this bug resurfaced and now is haunting me again.

Other cases?

• My iPad 3 iOS 7.1 is from Hong Kong, doesn't have this bug and I use the same Wi-fi connection as my iPhone.
• My girlfriend has an iPhone 5 iOS 7.1 (US) and iPad mini 2 (CN), she didn't experience this issue.
• My colleagues has Chinese phones just like mine (iPhone 4S w/ iOS 7.0 and iOS 7.1), didn't have the issue.
• Searching in Google and this community, it seems people are expering the same issue.

I am doubting that this bug has anything to do with my hardware or my settings. I feel this is a iOS software issue. Please let me know what I can do to help as I've already tried everything I can think of.

Thanks,
Bruce