Assertion error with IOStore in UE 5.6

When trying to run my packaged application built in UE 5.6 with the IOstore option turned on, I get the following error:

Assertion failed: GDefaultMaterials[Domain] != nullptr [File:D:\build++UE5\Sync\Engine\Source\Runtime\Engine\Private\Materials\Material.cpp] [Line: 606]
Cannot load default material ‘engine-ini:/Script/Engine.Engine.DefaultMaterialName’ [Domain=MD_Surface] from path ‘/Engine/EngineMaterials/WorldGridMaterial.WorldGridMaterial’

However if I turn the IOStore option off and build with just the Pak option the application runs fine.

I’m having exactly the same problem in 5.6
Have you installed the 5.6.1 Hotfix?

It’s a long shot, I’m not sure if that will help, but you could try running with the game with the -NoZenLoader argument.

not helped