Channel 3 and 4 not working in TP4

I am wanting to upgrade to tp4 but on the demo version I’m getting no sound from channel 3 and 4 when connected to the dim a9. The software is recognising the track playing as I’m seeing a feed but no audio from the mixer when trying to output on the third and fourth channel. If I switch to the second then it’s fine. Is this a limitation of the demo or am I missing something in the settings. I have all the exact same ones as TP3. Don’t want to upgrade if it’s not working.