Foliage Trees' Impostor LODs not working after migrating from 4.26 to 5.1

Development World Creation
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3

Hello RecourseDesign, how nice from You, thank You very very much:

Imposter2
Imposter22139×1193 225 KB

Imposter1
Imposter12010×1176 385 KB

I just migrated from UE4.27 to U5.1 and I cannot figure out what the problem could be.
Kind regards.
Harry