I did a service restart and noticed this:
2018-03-04 18:50:31.791 [INFO ] [voicerss.internal.VoiceRSSTTSService] - Using VoiceRSS cache folder /var/lib/openhab2/voicerss/cache
2018-03-04 18:50:31.827 [ERROR] [.voice.mactts.internal.MacTTSService] - Error while executing the 'say -v ?' command: Cannot run program "say": error=2, No such file or directory
It might have been caused by myself but am not sure where would I have added that command.