I have Magento CE 2.2.6 and one page checkout. I've set up Google Analytics per the built in configuration. After a few days I've discovered that a percentage of our orders are just never getting to GA at all as orders. For instance during a period of time we show 3 orders came in via the Orders tool but GA only shows one.
It appears that the ones that are not tracked are Guest orders (customer does not have an account with us).
When I place test orders in dev I can see a difference in the URL that gets called by analytics:
Guest orders on the thank you page call the URL
https://www.google-analytics.com/r/collect while logged-in orders on the thank you page call
https://www.google-analytics.com/collect. I'm not sure if that is the cause of the lost orders but it seemed like it might point us in the proper direction. I was unable to find anything explaining what the /r/ means. All of the other passed parameters look correct and the GA Tag Assistant doesn't show any problems with the fired pixel.
Thank you for any help.