Hi escalade,
Just for information, I solved my sound problem !
The update switched the default sound output from HDMI to Analog ; but when I reverted it, I still did not have sound in Kodi because I noticed yesterday that if you use a gamepad to navigate the menu, the Kodi sounds don't play ; but if you use a remote like Yatse on Android for example, they work !
Also, I had to change the sound output in Retroarch too, by adding the HDMI output manually to the "sound_device" line in reotrarch.cfg.
Now everything works !