You added your screenshots as Google Drive links (it's why they take a second to load), which unfortunately isn't the same as linking an image. I bypassed this by adding a hidden image at the top in your thread, it's up to you if you want to remove the hidden image and replace the Google Drive links with real images or just change the hidden image to another screenshot whenever you want.
My imgur tutorial is here if you want it!
I inspected the thumbnail in my browser and it linked to the old Hermine attachment, not sure how the forum decided that was the first image (which was then broken). I deleted the Hermine attachments and now it looks to be working again with the proper thumbnail image!