Hi,
I’d say it’s possible that it’s the same reason as mentioned in Customer not tracked - #2 by Lukas.
- the user was using an adblocker that blocked Matomo
- the user has disabled JS or blocked all third party scripts
- the user has enabled DoNotTrack and therefore their visit isn’t tracked by Matomo
- the user has used the OptOut iFrame to OptOut of tracking and is therefore not tracked.
- There is an error with your webserver causing some requests to be dropped (e.g. by using mod_security)
- There was an PHP error when the data should have been stored.
But other than that I can only ask the obvious question: Why would someone be fine with their personal data being tracked (assuming you don’t anonymize them)?
Why would I not immediately go to another site that doesn’t interupt me before it even shows me what the content is and why I would want to see it and instead go to a website that doesn’t track me or only tracks me in an completely anonymized way?