I have noticed an odd behavior when working on Google Analytics. I have enabled a custom dimension in an existing installation, and then started sending hits to GA with said custom dimension in it right away. (For clarification, this was a previous custom dimension, which was disabled and set to Product scope; I enabled it, renamed it and changed it to User)
The odd thing is that for a while, whenever I tried to show my custom dimensions in reports, I got an empty list, as if there were no hits with custom dimensions in them - even though I'm certain that they were being sent. However, a few hours after I tried again and I checked that this time around, the custom dimensions did appear in my reports - I could add them as a dimension to my reports and get back some results.
What bothers me is that when I checked the times of the rows I was getting in the report, it appears as though I only got results from the attempts I did several hours after setting the custom dimensions - apparently, the first hits weren't getting any custom dimensions with them.
So my question is - is there a setup period for creating or modifying custom dimensions during which GA will not record the new dimension data? Or could it be that I am overlooking something in my setup? (I'm pretty certain the clients were sending the right data at all times.)
Yes, in my experience it can take up to 3 hours (depends on a lot of factors). So next time anticipate the need for the custom dimension or just be ready to lose some data.