Missing file permissions / access for other needed after Upgrade to 3.1.13

Hi all,
After my recent upgrade to ISPConfig 3.1.13 (Debian Jessie) I have file permission errors on the ISPConfig panel.

I did a

Code:

find /usr/local/ispconfig/interface -type d -exec chmod o+x {} +
chmod -R o+r /usr/local/ispconfig/interface/web

and everythings runs fine - but I do not understand why this is needed, since www-data is member of ispconfig group ans so I expected those permissions to work:

Code:

#ps -aux |grep apache
www-data  3432  0.0  1.0 487248 42616 ?        S    17:24   0:00 /usr/sbin/apache2 -k start
...
www-data 19242  0.0  0.1 183500  4756 ?        S    06:25   0:00 /usr/sbin/apache2 -k start
root     28505  0.0  0.5 476912 22308 ?        Ss   Oct22   0:07 /usr/sbin/apache2 -k start

#id -Gn www-data
www-data ispapps ispconfig client1

# ls -als /var/www/ispconfig
0 lrwxrwxrwx 1 ispconfig ispconfig 35 Oct 22 16:28 /var/www/ispconfig -> /usr/local/ispconfig/interface/web/

~# ls -als /usr/local/ispconfig/interface/web
total 132K
4.0K drwxr-s--- 19 ispconfig ispconfig 4.0K Aug 31  2016 .
4.0K drwxr-s---  9 ispconfig ispconfig 4.0K Aug  2  2016 ..
4.0K drwxr-s---  6 ispconfig ispconfig 4.0K Jun 16  2016 admin
4.0K -rwxr-x---  1 ispconfig ispconfig 3.2K Dec 19  2016 capp.php
4.0K drwxr-s---  6 ispconfig ispconfig 4.0K Jun 16  2016 client
...

But I need

Code:

#
ls -als /usr/local/ispconfig/interface/web
total 132K
4.0K drwxr-sr-x 19 ispconfig ispconfig 4.0K Oct 22 18:40 .
4.0K drwxr-s--x  9 ispconfig ispconfig 4.0K Sep 24  2016 ..
4.0K drwxr-sr-x  6 ispconfig ispconfig 4.0K Sep 24  2016 admin
4.0K -rwxr-xr--  1 ispconfig ispconfig 3.2K Oct 19 15:45 capp.php
4.0K drwxr-sr-x  6 ispconfig ispconfig 4.0K Sep 24  2016 client
...

to get ISPconfig accessable.

(For the few sites running on that host nothing changed after the update - everything runs fine.)

Any glue what went wrong here??

Thank you!