Internally I transitioned our users over to a new Sametime 9.0.1 Community server with audio and video, meetings, TURN server, the works and it all worked, apart from file transfer.
When opening a chat window, the file icon would show but after about 1-2 seconds it would disappear. If you were quick enough you could send the recipient a file.
I checked all the policies, I checked policies.user.xml, I updated managed-settings.xml, I enabled trace on the client which showed it was enabled and I tried various configurations and all of which show that file transfer (both direct and via the server) was enabled.
The L3 IBM’er came back with the following
Next I looked at sametime.log and I see ST filetransfer is not staying started and suspect this is why the client can’t file transfer and they see the file transfer but show up and then go away::
I stplaces 28/Feb/17, 19:27:41 Places is operating in mode RELAX (1)
I stfiletransfer 28/Feb/17, 19:27:41 ChatLoggingMgr::setMode: mode <1>
E stfiletransfer 28/Feb/17, 19:27:41 Failed to load chatLogging BB or find one of its functions
E stfiletransfer 28/Feb/17, 19:27:41 Logging initialization failed for ChatLog library 
I stfiletransfer 28/Feb/17, 19:27:41 Terminated
I stlogger 28/Feb/17, 19:27:41 Initialization completed
I stchatlogging 28/Feb/17, 19:27:41 ChatLoggingMgr::setMode: mode <1>
E stchatlogging 28/Feb/17, 19:27:41 Failed to load chatLogging BB or find one of its functions
E stchatlogging 28/Feb/17, 19:27:41 Logging initialization failed for ChatLog library 
I stchatlogging 28/Feb/17, 19:27:41 Terminated
Chatlogging being enabled when it actually does not exist causes these type of errors and I see in the stconfig.nsf -> Communityservices document,
that yes chat logging is enabled and in relax mode:
But in sametime.ini there is no chatlogging enablement statements:
If no chatlogging software then they need to set the setting Flag: off and Type: 0
I updated the values in the SSC which updated the document in stconfig.nsf and after a restart of the Community server file transfer is now available!
The default is to set the following value to “when available” but setting it to “never” worked for me.
Update – 27/04/17
IBM told me that with 9.0.1, out of the box, this option is disabled by default. As this was a 126.96.36.199 server upgraded to 9.0.1 it may have been the case that 188.8.131.52 had this enabled. Or, I may have set it accidentally….
Update – 28/04/17
IBM posted the Technote yesterday – https://www-01.ibm.com/support/docview.wss?uid=swg22002683&myns=swglotus&mynp=OCSSKTXQ&mync=E&cm_sp=swglotus-_-OCSSKTXQ-_-E