It is not possible to select one of multiple connected Sigma LA. Reference implementation in LA8/LA16 driver: http://sigrok.org/bugzilla/show_bug.cgi?id=504 https://sigrok.org/gitweb/?p=libsigrok.git;a=commit;h=67f890d5bb259539b930df15146f138974a849de
Fixed in 53a939aba599af471fc82101c823ec7e4d574ac9, thanks!