samba - Jul 2016 - File Corruption on copy between folders in share (OSX SMB3.02)

I'm running a system with FreeNAS that uses Samba 4.3.6 and vfs_fruit to
serve files to my clients.

Compared to forcing everybody to NT1 (which we did before vfs_fruit) the
user experience is much better.

However, I am experiencing a strange problem I've only see reported a
handful of times.

When copying a large file (~38 GB in my example) from one folder to another
on the same share, I get the file copy dialog and "estimating time"
and
then it goes away rather quickly.

This leaves behind a file in the destination folder of the same exact byte
count and proper header (ie it still knows it's a QuickTime movie) but is
unplayable.

When I copy the file to another share on the same server, I get the full
copy dialog and the copy lasts the expected amount of time (instead of
ending almost instantly).

I do not have "fruit:copyfile = yes " in my config, but I'll try
it when I
have a moment just to see if it helps.

Is this a known issue?  If so is there a fix (other than forcing back to
NT1 which causes a whole bunch of other problems)?  If not, what data can I
provide to help?

Thanks
-S