Below is the answer I received from Presonus. After following these instructions Talk Back now works! The difference for me was to make sure I engaged the 'Custom' button on the CS in the TB section (see #3 and #5). Using this method, I Did Not have to change Ch 31 or 32 to Network. After following the steps below, just make sure 'mutes' are off and the TB fader is up on the aux(s) you selected. The example below uses aux 15/16 which are my linked IEM aux channels. You should substitute 15/16 with whatever aux you want to use for TB.
To have the Talkback Channel assigned, you'll need to assign the TB input using the Edit button on the Talkback setup.
As an example setup, try this:
1. Select the Edit button on the Talkback section
2. Assign TB input; use the CS18 TB 1 as the input from the Dropdown menu.
3. While in that same screen, assign the Custom TB assignments to Mix 15/16. Exit the menu by dis-engaging the Edit button.
To test whether the TB is going to the mixes (Need headphones):
4. Press the 'Edit' Button in the Monitor / Headphone Section. Assign the Cue source to be either 15 or 16 (currently, cannot Cue select a Stereo Link Aux in Cue output). Exit the Edit screen.
5. Now, engage the Cue button in the Monitor Section, then engage the 'Custom' Button in the TB section.
6. Now engage the 'Talk' button to turn on the Talkback. You should hear the TB source.
Technical Support Rep