BP Static Mesh Components are not retaining the vertex color applied to them in a level when you play in Standalone or Package a Project. You will get the correct results however when you PIE.
This was also Reproduced in 4.10.4, 4.11 Preview 7 and Dev-Main-CL-2900980
This could be related to UE-20583 as well.
RESULTS: BP Actor does not show Vertex Paint
EXPECTED: BP Actor should Retain Vertex Paint as shown in simply PIE-ing
Head over to the existingAnswerHub thread and let us know what's up.