looks like I just got bitten by this. When I got my 6sPlus I restored a backup from my 6plus. Siri suggestions were working on the 6Plus, but never worked on the 6sPlus. Tried a number of things to reset Siri Suggestions. None of them worked. Today I tried the Reset All Settings ... it's been over an hour and I'm stuck on a white screen with a black apple logo. Ill give it another hour, but looks like I will be wiping it, and installing everything from scratch if it doesn't recover. This is the first iPhone migration I've had significant problems with.