When using the Engine's High Res Screenshot tool, there is a limit on the amount of foliage that can be present before the meshes stop appearing. This number is around 1500 meshes, though I was not able to get an exact number. This issue appears to be a regression, as this does not occur in engine version 4.16
4.16.3 - CL: 3561208 - Issue does not occur
4.17.1 - CL: 3586342 - Issue occurs
4.18 - CL: 3597901 - Issue occurs
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