Update: Using the Utopic Unicorn (active development) package pidgin-sipe 1.18.2-1 resolves the problem. Go here http://sipe.sourceforge.net/ to download it and select your distro under 'Ready-to-use SIPE installation packages for various distributions'.
Andrzej.
If you would like to refer to this comment somewhere else in this project, copy and paste the following link:
Please see this thread. Is anyone working on this?
https://sourceforge.net/p/sipe/discussion/688534/thread/dd12cdc6/
Andrzej.
Update: Using the Utopic Unicorn (active development) package pidgin-sipe 1.18.2-1 resolves the problem. Go here http://sipe.sourceforge.net/ to download it and select your distro under 'Ready-to-use SIPE installation packages for various distributions'.
Andrzej.