I have a couple of problems with Google Analytics API.
1) Certain data pulled from the API is changing retroactively - especially the number of "not set" sessions. The data I pulled last month no longer match with the data returned by the API (for the same query, profile and dates). For instance, last month I got 120 "not set" sessions and now I am getting 1930 "not set" sessions.
2) There is a dramatic increase in the number of "not set" sessions. This affects historical dates as well.
So it looks like the historical data was modified - specifically all the data > August 2013.
I also noticed the overall number of sessions (total number of sessions for all metros) stays the same. However the "not set" sessions is way much bigger and then each big metro has less sessions (somehow the attribution changed but I have no idea how and why).
Any idea what is causing these discrepancies? I thought the historical data is static and not changing over night without notice. I am really confused.
Thank you for your help.