There's a bug when two particular images on Obsidian Core fail to load. Note; Not sure whether or not this is client side.
Viewing post in Bug Reports - Help Me Fix Issues!
Where are you experiencing this? On spaceoverlord.io or on itch.io?
Either way, I don’t see why this would happen - these are just lightweight assets. The only possible cause I can think of is a slow internet connection.
If you haven’t already, try installing the PWA. While playing, it downloads and stores all the assets locally so you can play offline.