By default, the Enlighten data generated by the precompute is stored within each .umap file. You can't run the precompute and save the Enlighten data when the .umap is locked for editing by another user. This makes it difficult to collaborate on levels.

To resolve this, move the Enlighten data to a separate .uasset file.

Load the level you want to change.
Select all the Enlighten System Container actors.
Under Details > Enlighten Settings, expand the advanced options.
Under the Move drop-down menu, select To Asset.

This moves the Enlighten data for the selected Enlighten System Container actors to .uasset files in the same folder as the .umap file.
Select File > Save All to save your changes to all modified assets.

File > Save saves only the current level. It doesn't save Enlighten data stored in a separate asset. Use File > Save All to save all modified assets.

Restore Enlighten data to a level file

Load the level you want to change.
Select all the Enlighten System Container actors.
Under Details > Enlighten Settings, expand the advanced options.
Under the Move drop-down menu, select To Level.
The .uasset file is deleted.
Select File > Save All to save all modified assets.

Locate a level's Enlighten data

To find the precompute data for a level, select its EnlightenSystemContainer actor. The Precompute Data value in the Details tab displays the name of the asset that contains the Enlighten data, or displays "In Level":

Enlighten data stored in asset	Enlighten data stored in level

If the precompute data is stored in an asset, you can use the button to locate it in the Content Browser.

Add a sublevel

When you add a sublevel, if the Enlighten precompute data for the persistent level is stored in an asset, the precompute data for the new sublevel is moved to a new .uasset file if necessary.

If you duplicate a .umap file using Windows explorer, its link to the Enlighten data .uasset might be corrupted. To avoid this, duplicate the .umap using the UE4 editor.

Rename a level

When you move precompute data to an asset file, the .uasset file appears in the same folder as the .umap file, named <mapname>_EnlightenData.

When you change the name of a level, the name of the .uasset file no longer matches the .umap. Enlighten gives you the option to automatically rename the .uasset to match.

After you move the data to match, choose File > Save All to save the modified assets.