Contents of Bundle in Firebase Analytics Event not showing in dashboard

I have the same issue as this thread but the answer is outdated and seems to be incorrect. It refers to a button "Add event parameters" which is not present in the current version of firebase.

I want to view the content of the bundle for the event on my Firebase event page. Here is my event page on firebase:

I've followed this firebase tutorial and here is my code:

    private fun sendLogging(context: Context, source: String, logMessage: String) {
        val bundle = Bundle()
        bundle.putString("LOG_MESSAGE", "$source $logMessage")
        FirebaseAnalytics.getInstance(context).logEvent("PUSH_CONTENT_NOT_RECEIVED", bundle)
    }

The source and logMessage contain precise information about what went wrong and I need to view this. It should show up?

EDIT:

I went to "Custom Definitions":

And I've added the event:

I discovered that only from that moment it started collecting information, so the information of the spike of a few weeks ago is not collected.

But as can be seen in the image below, the string is shown only partially, only the first and last 10 characters:

from Contents of Bundle in Firebase Analytics Event not showing in dashboard