If the investigative material is actually rather good, and way better than I initially guessed at, then I wonder where the discrepancy between my initial judgment versus my later investigation came from.

It's quite easy to convince a person that's ignorant of something that isn't true. Your argument that you were ignorant before you looked at one-sided investigative material doesn't make you a trustworthy source.

Were I the victim of some sort of bias before I started to investigate more thoroughly? Why were I so quick to judge, emotionally, at a point in time where I didn't have any knowledge about whether high quality studies existed on the topic or not?

You didn't reason clearly about the subject. If you think there a case with good evidence and you instead used "Je Suis Charlie", that's a major blunder.

Not putting in your best effort to make your case protects you from falsifying your belief.