The only difference is one letter… “focusId” vs “FocusId”. This is a large issue since links may be placed on the website, email campaigns, search engine marketing ads, etc. One or more letters of the URL could easily have different cases from one location to another.
Thanks for reaching out to the target community. You should use "URL" as the refinement for the activity location. Hence In this case it will be a good idea to use the unique part of the the URL in the activity location condition for the refinement and it will be case Insensitive. Lets take your use-case and say that "http://www.domain.com/default.aspx?FocusId=best-sellers-pen-sale.ascx" remains same for all the url variation except the fact it may vary in terms of cases such as "http://www.domain.com/default.aspx?focusId=Best-Sellers-pen-sale.ascx".
So please set the condition like the below snapshot :
We have tested it at our end and it works when it works independent of the cases.