Hey there, dragging up an old thread incase it's helpful to others down the road, I spun my wheels quite a bit before I realised what the issue was.
Modules cannot be loaded in the /storage/.config/pulse-daemon.conf.d/ file. It is only used for changing pulse audio settings. Like the ones listed here
If you need to load a module, you must use /storage/.config/autostart.sh (Autostart.sh [LibreELEC.wiki])
In my case I simply added these lines for loading RTP multicast receiving on boot.
Code
pactl load-module module-udev-detect
pactl load-module module-http-protocol-tcp
pactl load-module module-rtp-recv