Everybody's reputation is 0

I was up to a reputation of 4 or 5. At this point I forget what it was. Then one day my reputation went to 0. When I visit friends, their reputation is displayed as 0. It used to be when I left a tip for a friend my reputation would increase by 1. Now, I get no increase in reputation no matter what I do. When I search for information on reputation all I find are discussions on reputation maxing out at 51 which is not my issue.

Does anybody have any insight?

I am not sure if it is a factor but I am using an iPhone.