Don't know.
CFW/ATV v2.1.1-v2.1.7 use same official Kodi 18.2
mirrors.kodi and preset for passthrough,
AC3/AC3-Transcode/E-AC3/DTS with AudioOutput 2.0.
Preset settings for E-AC3 passthrough is false start with v2.1.5 as that not rely supported.
If you still run CFW/ATV can try uninstall Kodi, install Kodi 18.2(mirrors,futeko,mediafire) reboot box, wait 2-3 minutes after box rebooted, open Kodi 18.2 will see is present for passthrough then check if is running well for you.
Note: Use play with VideoPlayer to not be tricked then get play with Wrapper&HiMediaVideoPlayer.