@hhs2112,
I can replicate it too, but it seems to be due to the share itself.
I've got a USB drive but only SHARE 2 sub-folders. I can copy to those sub-folder but NOT to the top level root of the drive.
====================
C:\>net view \\tp-share2
Shared resources at \\tp-share2
samba server
Share name Type Used as Comment
-------------------------------------------------------------
G Disk
The command completed successfully.
C:\>dir \\tp-share2\g
Volume in drive \\tp-share2\g is G
Volume Serial Number is 061B-373A
Directory of \\tp-share2\g
09/18/2019 07:13 PM <DIR> .
09/18/2019 07:13 PM <DIR> ..
09/24/2019 07:33 PM <DIR> Pictures
05/12/2018 11:25 AM <DIR> share
0 File(s) 0 bytes
4 Dir(s) 1,208,233,320,448 bytes free
---------------------------
Now trying to copy to G (which is NOT really shared, and then a sub-folder:
==================
C:\>copy l:\test.txt \\tp-share2\g
Access is denied.
0 file(s) copied.
C:\>copy l:\test.txt \\tp-share2\g\share
1 file(s) copied.
===================
Is this similar to what you were trying to do?