Textures are missing in Standalone Game - 4.14.1

Hi,
at the moment I make some tests with Ansel. But in my current project the leaves of my trees are not rendered correctly when I start a Standalone Game. (only small planes without the textures are visible) In every other mode the leave textures are there. For this reason I deleted the whole “saved” and “intermediate” folder. But without success. This problem occured after the conversion from 4.13 to 4.14.1.

Best regards, Andreas

UPDATE:
In the meantime I found the solution for this problem: