I’ve seen there are a couple of old posts related to this, but I see that it is still not fixed, so just to check up with you:
To track activity coming from Google AdWords in Google Analytics, and also to return conversion information to AdWords, Google AdWords add a param ?gclid=XXXXXXX to the destination URL. The problem is that, if you have A/B testing active, your plugin cleans up the URL and that parameter is lost, causing Analytics not detecting the visitor is coming from AdWords. I think that sometimes it cleans the URL and other it doesn’t but I’m not sure.
This is very important because we use landing pages mainly with AdWords, and cannot have feedback from analytics about conversions, which is very important to improve AdWords performance (and save money).
I have disabled AB testing and it works fine now, but I think you should solve this issue as soon as possible, so that we can take advantage of A/B testing over AdWords campaigns.