Google Analytics 15 Piwik 0

Recently I installed Piwik on 4 of my joomla websites, I still use GA on these websites too.
Yesterday my main website scored 15 visitors in one day, but the same website scored 0 visitors with Piwik the very same 24 hours!
I am confused, doesn’t my Piwik stats website work properly? Or is this okay?

Piwik should track all visits, unless they were all yours or someone excluded with IP, Do Not Track, etc. ?

Also have a read on: Troubleshooting - Analytics Platform - Matomo