Google Analytics API Issues

[alz.an...@gmail.com]

Hello,

I am having a couple of different issues related to Google Analytics API which may be related.

1) Location data is changing retroactively

2) "not set" data is increasing

3) This is not an API versus Google Analytics Interface issue, as we see the problems in the GA interface as well.

1)

- we see this especially in the metro area report;

-what happens is the "not set" visits and certain metro areas change from one day to another;

-we see this issue in all the metro areas with about 30% of them changing value, and the "not set" data increasing value (and other metros are decreasing or disappearing);

-the total visits remain the same, however;

2)

-we pull metro area visits daily through a windows service and save them into the database (no sampled data);

-this data has in the past been validated against a manual Google Analytics Interface pull, and they matched almost 100%;

-we've recently re-pulled the data manually, and see data changing from August 6th 2013 to October 12th 2015 (the database data never changed and now the data from Google Analytics Interface is different);

-however, starting October 13th 2015 the database values match the data returned from the Google Analytics Interface (but the "not set" visits is higher than it used to be);

3)

-all data have been validated in the past;

-reports from last year no longer match the data returned from the Interface;

Why is the data changing?  Are the visits we're seeing real?  or are they part of some Google Analytics bug or spam issue?

How should I proceed?  

Thank you and I appreciate your help.