I actually had this problem once.
if i remember right you should go to your sparkpost account select Account -> SMTP relay and click "ENABLE tracking"
Then it should work.
Already make the change with a normal url and perform the click and still do not appear in the statistics.@Carlos Martinez - There's def. something wrong with your sending settings or something.
Looking at what you sent at https://www.mail-tester.com/web-ns1r8 i can see there is no tracking link for opens in the email footer.
Also i see the only link in email is not converted into a tracking link, but it's still a short link.
Check your campaigns settings, try with another template...