Hello @Mattuati,
As the output sockets of the QU range are fixed to an output bus, please make sure you are connecting your speakers to the L&R output sockets.
Alternatively, as Mike C has advised, PAFL the Main Mix instead of the individual drums channel to make sure that the signal is in fact going to the Main Mix.
As a side note, the latest firmware available is V1.97, it is always good to stay up to date with firmware versions; so kindly update.
If you encounter any further issues, please submit a ticket at our support centre and I will gladly troubleshoot it with you:support@allen-heath.com
Thank you,
Rafael