Bixby no longer makes a sound when you push the bixby button and open the app after the update in April 2022 on the s6 tablet. I have cleared the cache, the sound is all the way up in Bixby. I have called support and they said factory reset. I didn't update my work tablet first so I tested it out and had sound when I pushed the button opening sound was there. I updated it and the sound was gone. As for the factory reset I will not do that as the sound no longer works on my Galaxy 20 phone, my work s6 tablet, my nieces Galaxy 20 phone, her dads Galaxy 21 phone. It doesn't work on my coworkers company phones and tablets either. The carriers are Verizon and veiro for phones and work tablets, wifi for my tablet. The tablets are the same as my autistic and visually impaired daughter s6 tablet. For some reason she likes the sound. This is not a tablet issue it is an update issue.
Just tested and the Bixby button doesn't make a sound for me either. This may be a feature and not a bug I'm not sure. You can try filing an error report and see what they tell you.
