Following command produces 0-byte output file: sigrok-cli -d fx2lafw --samples 100 --output-format wav --output-file out or sigrok-cli -d asix-sigma --samples 100 --output-format wav --output-file out Linux Mint 18, latest source code snapshot from sigrok GIT.
This is not a bug per se, the WAV output format only supports analg data (not logic/LA data) at the moment. I guess support for logic data could be added as well though, if someone feels inclined to extend the WAV output module.