add attribute when proxying

[denis]

Hello,

I have setup made according to robust proxy accounting guide.
Now I need freeradius to add Tmp-String-1 attribute to each Access-Request
sent to proxy.
I tried using policy conf and ulang in robust-proxy-accounting config, but
request sent to proxy is still unmodified
One of log examples (just for curiosity i'm trying update both -
proxy-request and request:

(0) server home.mycompany.com {
(0)   # Executing section pre-proxy from file
/etc/freeradius/sites-enabled/robust-proxy-accounting
(0)     pre-proxy {
(0)       policy add-attribute {
(0)         update request {
(0)           Tmp-String-1 := 1111111
(0)         } # update request = noop
(0)         update proxy-request {
(0)           Tmp-String-1 := 1111111
(0)         } # update proxy-request = noop
(0)       } # policy add-attribute = noop
(0)       policy debug_proxy_request {
(0)         if ("%{debug_attr:proxy-request:}" == '') {
(0)         Attributes matching "proxy-request:"
(0)           &proxy-request:User-Name = username
(0)           &proxy-request:User-Password = password
(0)           &proxy-request:NAS-Identifier = nasid
(0)           &proxy-request:Framed-Protocol = PPP
(0)           &proxy-request:Service-Type = Framed-User
(0)           &proxy-request:Event-Timestamp = Jun 29 2017 13:51:01 UTC
(0)           &proxy-request:NAS-IP-Address = 185.7.90.32
(0)           &proxy-request:Message-Authenticator := 0x00
(0)           &proxy-request:Proxy-State = 0x313636
(0)           &proxy-request:Tmp-String-1 := 1111111
(0)           EXPAND %{debug_attr:proxy-request:}
(0)              -->
(0)           if ("%{debug_attr:proxy-request:}" == '')  -> TRUE
(0)           if ("%{debug_attr:proxy-request:}" == '')  {
(0)             [noop] = noop
(0)           } # if ("%{debug_attr:proxy-request:}" == '')  = noop
(0)         } # policy debug_proxy_request = noop
(0)       } # pre-proxy = noop
(0)   }
(0)   Proxying request to home server 138.7.90.9 port 1812 timeout 30.000000
(0)   Sent Access-Request Id 19 from 0.0.0.0:30848 to 138.7.90.9:1812
length 101
(0)     User-Name = "username"
(0)     User-Password = "password"
(0)     NAS-Identifier = "nasid"
(0)     Framed-Protocol = PPP
(0)     Service-Type = Framed-User
(0)     Event-Timestamp = "Jun 29 2017 13:51:01 UTC"
(0)     NAS-IP-Address = 185.7.90.32
(0)     Message-Authenticator := 0x00
(0)     Proxy-State = 0x313636
Waking up in 0.3 seconds.


As you see proxied request is unchaged, while debug output above states
attribute was  added.
For example if in same way I modify existing attribute - this will work
fine, i.e Framed-Protocol will be sent to proxy with value I set.
update proxy-request {
    Framed-Protocol := 11111
}

But I need new attr added, and now I'm completely out of ideas how to
achieve this. Already read lots of mailing archives, unlang doc and etc -
still do not understand how attribute can be added.
So if someone has any idea - please point me to correct doc/direction.
freeradius 3.0.12

--
Denis