The cover must not be set if:
The cover image is duplicated in the article.

It's content issue, but since they have the same url with the size at the end, it's reliably identifiable and should be removed.
cover: https://intraday.my/wp-content/uploads/2019/02/AUDUSD-1.2.2019-750x430.png
(full) image: https://intraday.my/wp-content/uploads/2019/02/AUDUSD-1.2.2019.png

Please see:
https://instantview.telegram.org/contest/intraday.my/template157/issue1/
"Unless a competing template is able to show that it can reliably identify and remove these duplicates, this is a content issue, as opposed to a template issue"
My template is, and it's a competition, so it can be considered as a template issue now. The duplication is common is such Analisis articles, examples:
https://intraday.my/analisis-teknikal-usd-jpy-timeframe-h1-1-2-2019/
https://intraday.my/analisis-teknikal-usd-cad-timeframe-h1-1-2-2019/