Aspen tree from soul cave not compiling in standalone/packaged game

images: noncompiling tree ue4 - Album on Imgur

found the answer: "To reproduce: 1. Migrate custom content into your project via Epic Launcher (for example the KiteDemo project) 2. (step to confirm) Use a personal directory structure, sodrag’n’drop Materials/Meshes with “copy here” 3. Add meshes to the foliage tool and draw them in the editor

Everything looks nice in the editor, but running the actual game will cause missing textures (and sometimes even messed up meshes).

Fix as mentioned: Change something trivial inside one of the migrated materials and save. All migrated materials/meshes are now displayed correctly in the actual game."