Guys, been following this thread for a while and finally I think I may have found a solution. Worth a shot, it worked for me.
Here's the background (parameters of sorts)
Phone : iPhone 6, 64Gb
OS : 9.0.2
Siri Settings : ON
Spotlight Settings : Siri Suggestions : ON
Turned off ALL search results except for CONTACTS
Problem started since iOS 9.0 upgrade, and persisted till now. In between, I've also tried all the suggested solutions proposed in this forum but none worked except for one (which incidentally was meant to solve another issue regarding mobile data toggle on/off). Now I have to highlight a few key points here, I did 3 attempts to wipe out my phone before finally came to my current solution. The first 2 attempts sort of led me into my third (hopefully final) solution. So please stay with me:
First attempt that failed:
1) Wiped and restore phone from iTunes (Spotlight search contact worked),
2) Restore iCloud backup.
3) Spotlight search failed after this
Second attempt that worked for one day :
1) Wiped and restore phone from iTunes (Spotlight search contact worked),
2) Don't restore iCloud backup.
3) Then phone started automatically downloading my iCloud Contacts (Note: this is still not a iCloud backup as my SMS and Recent Calls were not restored)
4) At this point Spotlight search contact still worked
5) Proceeded to add my Gmail account
6) Problem recur after a day of use.
7) Deleted Gmail account didn't solve the issue
Third attempt that worked (2 days on and still working as I type this)
Step 1 to 5 same as second attempt, after this, since now I know it's got something to do with Contacts and Mail account, I did the following:
(NOTE: You can try the steps below immediately to see if it works without resetting the phone)
Goto Settings -> Mail,Contacts, Calendars -> Short Name (under CONTACT at bottom of page) -> do 2 things here:
Prefer Nicknames = OFF
Select : First Name & Last Initial
Not sure why or how but I did counter check every setting between my iPhone and my iPad (9.0.2, didn't have this problem) and after many rounds of trouble shooting in the contacts / mail settings, it just worked. Refer to screens below.
Hope this helps. Will keep updating you guys if this solution stops working.


