I had an article do something similar it had a lot of views and reads but wasnt earning as much as past articles with similar stats. After you mentioned your article had more externbal views I checked the stats for mine, yes! 89% of that articles views were external. Only 11% came for Medium. I did have my normal call to action on it, but no luck.

I am so happy I came across your article as it at least gives some explanation as to why it performed so differently . Thank you!