Thanks for letting me know! The Ubuntu version is challenging for me to test because I'm doing it through VirtualBox. I just checked and the volume was indeed very very low. I had to turn the volume up on the Linux VM all the way, and then very high on my Windows audio controls as well. I'm not sure yet how to solve this, but I'll think about it. Thank you!
Thank you for your quick reply!
I don’t know exactly how, but I have sound back! I’m running Lubuntu 20.10 on a very old (Win Vista era) PC. I thought I would give Wine a try and I installed the latest Wine Staging and although it didn’t display any video because the iGPU is so old it’s not supported by Vulkan, it played sounds. So I go back to the native Ubuntu version and suddenly there’s sound. I’m thinking maybe I was missing libs or something. Anyway, thanks.
P.S. Try to reuse an old Mac and put Ubuntu on it for testing for you can.
That's great, I'm glad it works now for you! Yeah I should look into the libraries to see if any should be required. Maybe there's a list of libs for all GameMaker games.