If you don’t have processes in place to confirm (here’s mine), check whether your PX integration with Salesforce is properly matching contacts. 

We’re 10+ days into 40-50% of new users not matching despite no change to the integration setup in PX and no changes (that I”m aware of) on the Salesforce side. 

I’ve reported this to support and they are investigating, but I’m curious as to whether it’s impacting others as well. If not, I want to do more digging internally to confirm we didn’t cause this with a change on our side.