Hi, thanks for replying. Just to answer, I was able to open this project and other projects just fine. The problem was that opening the scene made the engine crash. However, the issue has been resolved (somehow).
Turns out Unreal saved temporary files, that it is supposed to delete automatically (in this instance, the troublemakers were 5 rocks that couldn’t be removed ; the crash may have stopped the process early).
Removing them fixed the issue entirely. I have no idea why this happened however, and have no idea how to recreate it.