@Humidor
The quickest check would be to repatch or double patch aux outputs which you know are working to SLink output sockets 10-12.
This will show whether it’s something related to patching or the AR2412 or something in the settings of the Auxes you want to use.
If this suggests it’s something wrong with the setup on the console, then the first place I’d look based on the info you’ve given, is whether you have the Aux sends set to pre or post.
For FX they might have been set to post, so if you have your channel faders (to main LR) down, or a DCA turned down, nothing will be being sent to post fade auxes.
All sends to an Aux can be switched between pre and post fade at one time in the routing screen – https://www.allen-heath.com/media/SQ_ReferenceGuide_V1_5_0.pdf#page=40&zoom=auto,-361,573
Or by selecting selecting the aux with the blue mix keys, holding the ‘Pre Fade’ key and pressing the Master strip ‘Sel’ key to toggle between pre (illuminated) and post (not illuminated).
Cheers,
Keith.