I don't know if this was always an issue as it's been a long time I didn't fly the 733. But today I made a short flight and I noticed the "Fire warn bell cutout" and "Master caution" didn't make any sound when pressed. Everything else seemed to work perfectly.
I'm on X-Plane 11.32 final, using IXEG 733 Classic 1.21 on Windows 7 x64.
Thanks!