Apologies for the slow response. It’s not anything that I have done to the course. I have noticed similar issues with other image-based courses (that are not mine), so it may be something that Memrise has changed.
Thank you for identifying some of the images you have been having issues with. I’ll check to see if there is common link.
OK It’s fixed again. Although most items had multiple images linked, a whole lot of them in the database were showing an empty image file in the first position. I have deleted those image files and uploaded replacements where necessary. I’ve no idea what caused that to happen. I don’t think any of the original images were in the wrong format. There are three or four previously unseen images now. The rest I have uploaded from my library folder.
Thanks again for flagging this up.