Copying values of an array created through C++ does not copy all values, only the first value is copied over. This is different than an array that is created in blueprints when those are copied they print out all the values of the array. This issue is not a regression.
Versions Tested:
4.15.3 - CL: 3450819
4.16.3 - CL: 3561208
4.17.1 - CL: 3586342
Issue occurs in all versions tested
There's no existing public thread on this issue, so head over to Questions & Answers just mention UE-48825 in the post.