Maps (.umap) are not appearing in Content Browser

Today when I opened UE some of my maps have seemingly disappeared from the content browser, despite no changes occurring. I’ve read through a dozen other questions on the answers hub of people reporting the same issue, and in all of those cases suggestions are given which are not applicable here:

  • I have not modified my version of unreal. This project was started in 4.22 and is still in 4.22.
  • No file changes have occurred. I’m using source control, and there have been no changes in my working project since the maps loaded correctly yesterday.
  • I have tried various versions of my project from over the past week, and they all now exhibit the problem despite working fine when I made them.

Whatever the problem here is, it must be related to some cached data inside the Editor, not my project. The Editor must be finding the .umap asset on disk, and then making some type of decision to not show that map inside the content browser. Whatever that logic is needs to be exposed to the user so that they can resolve the issue.

I would happily debug the engine source for this if anyone could point me in the direction of where in the source it does this check.

try to copy them into a new blank project to be sure. if you have 4.23 installed, try also in that one. open the map in a editor (or hex-editor) - keep in mind how big the file is it may crash your editor (depending on your editor), search for “++UE4+Release-” and have a look what it sais after that pattern. I guess you already checked the logs under the Save\Logs folder if the editor complains for something?