Hello Manu,
Thanks for the clear explanation of your setup

What you are seeing is expected behaviour in Cuety. The 24ch mode of this fixture uses multiple internal sections / sub-fixtures, so each LED section can be controlled individually. Cuety does not support sub-fixtures, so these modes are ignored in the Cuety patch list. That is why you only see the simpler modes.
The easiest solution is to use the 6ch or 10ch mode if you want to control the bar as one fixture.
If you really need individual control of each LED section, the workaround is to split the fixture into several smaller Cuety personalities and patch them as separate fixtures. For example, in 24ch mode you could make four separate “pixel” fixtures of 6 channels each and patch them with address offsets.
So if the real fixture starts at DMX 101, you would patch:
Pixel 1: 101
Pixel 2: 107
Pixel 3: 113
Pixel 4: 119
This uses more fixture slots, but it is the correct workaround for multi-section fixtures in Cuety.
Hope this helps!