Windows fileserver and ABE

I am in the process of creating a new Windows 2008R2 file server and have some issues with Access Based Enumaration.

I don't just want to migrate all data and permissions as our structure is grown over the course of the past ~15 years and to be honest it's a mess. So I am trying to put as much effort into this as possible.

I set up a domain based DFS-N (Data) where shares for each department (dept1 to dept 4) are published. While testing (yes, we have a test environment! Lucky us!) I stumbled across a bug(?) regarding Access Based Emuneration. Permission will be handled through nesting of different permissive groups. My problem is that adding a user to a specific group for a subdirectory does not enable him to see/traverse the parent directories.

ABE is enabled on both the fileshare and DFS-N.

I have created following directory structure:

\\DFSRoot\Data\
+---dept1
|   +---dir1
|   |   +---sub1
|   |   \---sub2
|   +---dir2
|   +---dir3
|   |   +---sub1
|   |   \---sub2
|   \---dir4
+---dept2
|   +---dir1
|   +---dir2
|   +---dir3
|   \---dir4
+---dept3
|   +---dir1
|   +---dir2
|   +---dir3
|   \---dir4
+---dept4
|   +---dir1
|   +---dir2
|   +---dir3
|   \---dir4
\---dept5
    +---dir1
    |   +---sub1
    |   \---sub2
    +---dir2
    +---dir3
    \---dir4
        +---sub1
        \---sub2

For each directory I created 3 groups:

So for \\DFSroot\Data\dept1 this would be

dl-dept1-list
dl-dept1-ro
dl-dept1-rw

For \\DFSroot\Data\dept1\dir1

dl-dept1-dir1-list
dl-dept1-dir1-ro
dl-dept1-dir1-rw

And for \\DFSroot\Data\dept1\dir1\sub1

dl-dept1-dir1-sub1-list
dl-dept1-dir1-sub1-ro
dl-dept1-dir1-sub1-rw

For everything else this scheme applies, too.

For each directory the corresponding groups are member of the list group of to next upper level directory. So

dl-dept1-dir1-sub1-list
dl-dept1-dir1-sub1-ro
dl-dept1-dir1-sub1-rw

are member of dl-dept1-dir1-list

Inheritance is not broken. Those RO/RW groups have their respective permission to their folder and every subdirectory within.

List groups have special permissions --> ListDirectory,ReadAttributes,ReadPermissions,Traverse --> This folder only

If I add $User to dl-dept1-dir1-sub1-rw to grant R/W permission to \\DFSroot\Data\dept1\dir1\sub1 the user is able to access the share dept1 (members of dl-dept1-list) but does not see any directories. $User cannot access dir1 via UNC path. $User can access sub1 via UNC path.

If ABE is disabled on share $user can traverse directories without problems.

At this point I'm stuck and don't see what I am missing.

Maybe one of you can help. Thanks in advance.