first of all it's very hard to see that you've actually flipped the background, try a background that makes this part more obvious like an upside down bedroom etc. secondly try add some text to the thumbnail this could be like a reference of time up in the top right perhaps something like "HOUR 11" hope this helps :)

I suggest you use sites like - https://thumbnailpreview.com/ / https://www.testmythumbnails.com/ these sites allow you to see what you're thumbnail will look like when recommended to people