It might be if you use search for different object types.

So you do one search on news that gives response and then one on events that gives no result.

I explain it a little here:
https://world.episerver.com/blogs/Henrik-Fransas/Dates/2015/2/how-to-do-custom-query-and-click-tracking-with-episerver-find/

@Henrik: Yes, we are searching on different object types, but we are following the approach described in your blog post. 
It might be related to the implementation of trackId (as mentioned in one of the comments).

Thanks for pointing  me in the right direction! :)

Glad to help!

Fun to see that you have one profile image when starting threads and another when replying to them, have you hacked Episerver World? :)

I have cloned my self while I was on parental leave :D

Thanks to Episerver support the issue is now solved:

The problem was that tracking of the query where using _statisticTagsHelper.GetTags(false) while tracking of the hit click was using _statisticTagsHelper.GetTags().