CitySample cannot be imported without errors

Hello you professionals.

I ask for your help. I’ve been trying to import the Small City Lvl of the CitySample into my test project for 3 weeks. But no matter which way I use, meshes are not found and the map is full of holes and the roofs hang in the air. Here’s what I tried:

  1. Using “Migrate” I only integrated the map into my test project and deactivated vehicles and crowds, but left all buildings activated. Nevertheless, individual meshes or entire walls are missing from many buildings. However, there is no error in the log file that something was not found.

  2. I then moved the folders to a new one as a 2nd attempt and then edited each one with Update Redirector References. To be on the safe side, I later selected Keep Redirectors. I then moved this folder to my test project. But again, the exact same error as with Migrate, only this time I get error messages, such as: [2025.03.06-07.04.07:990][ 13]LogStreaming: Error: Couldn’t find file for package /Game/Building/CH/C/Kit_Bldg_CHC_L1_A/Decal/SM_BLDG_CHC_L01_A_Wall_03_N1_decal requested by async loading code. NameToLoad: /Game/Building/CH/C/Kit_Bldg_CHC_L1_A/Decal/SM_BLDG_CHC_L01_A_Wall_03_N1_decal
    However, the asset is present in the folder. I then ran an update Redirector References in the CitySample folder under Content and copied the folders back into my project, with the same result. A resave all didn’t help either.

Can someone tell me what I’m doing wrong here?

Thank you for your help