As Logic is no PreSonus product, don't wait for support. If you're a Facebook user/member, this closed group might be interesting for you:
PreSonus StudioLive Series III DAW Mode
The term DAW Mode often seems confused. Basically, your mixer (SL 16) has two "hearts": It will work as "normal" live mixer and it will lend its faders and buttons and encoders to the DAW (while still functioning as live mixer). It's this combination, that makes the StudioLive mixers so special.
I am no specialist for Logic, but I guess it works more or less as Studio One, so you are not really "mixing" on the console, but inside your DAW. When a mix is ready in Studio One, it will be rendered to a separate stereo track, which can be mastered afterwards. Again, you are not mixing on the SL 16. The fader you are moving are the faders of Logic.
Hope this helps.