I also don't have sound after updating the game to the new version. The game was installed from scratch. System linux mint mate 19.3. In the older version of the game, the sound worked.
hi, I found a fix to one of the issues of the game, for some reason there is a issue with the config file and it makes the game unplayable, you cant even go to the main title screen or play the game, to fix this go to your yooka-laylee config folder and delete it, then run the game again, this will create a new config folder and file and will fix the issue of with the game being stuck on loading right before it even shows you the main menu.
the path to the config file for yooka layle is:
once there delete the entire yooka-laylee folder, then start the game, the game should now be playable but this does not fix the sound issue.
the only issue is that the game still has no sound. GOG support told me to contact firstname.lastname@example.org for help with the sound issue. I submitted an email to them but if you could help me with this I would be helpfull. please also open a case with GOG so that they will push this issue to the developers too.