Titan normally only outputs Art-Net when there’s actual DMX activity on a playback, so make sure a cue/fader is active and outputting values. Also check that the universe is patched and enabled for Art-Net output under Titan’s DMX settings. Broadcast vs. unicast can matter too—WLED sometimes behaves...

In Titan’s API, group usually refers to a programmed fixture group (the same type you create in the console under Groups). So if you already have fixtures stored in a group, you can reference that group name in the group parameter. The handleIndexList parameter refers to the internal handle indexes ...