Yes this is a know problem I got on my list. It is a weird edge case.
Problem is that at first it detected that D:\Source and E:\Link really are the same volume
And if you do a move on same volume, the file content is not copied. the entry in the filesystem is just renamed so it is located on a new path . Like if you did not go via the symlink.. Then D:\Source would just be renamed to D:\Target\Source and no need to copy data. But this does not work over a symlink.
There are also a couple of way to solve this. Problem is that both have there own issue and drawback.
Not even windows explorer is consistent..
Copy D:\Source to E:\Link it will resolve the link and do a rename
Copy from D:\Source to E:\Link\SubFolder it does a full copy
and copying from E:\Link to D:\ it will do a full copy.
I will see if there are some easy fix for this.