I'm assuming you tried this, but if not:
- disconnect the Apollo16 from the computer, and connect the Twin directly to the computer. Is this a TB 2 Twin or TB3? If running through a TB3-TB2 adapter, try changing the adapter and cable if possible, or if TB3 model, switch out the cable. Also try different ports on your computer.
If the Twin still doesn't work in that scenario, then it's a hardware problem, and you will have to send it back to UA to get fixed IMHO. If it does work, then the issue is coming from the daisy chaining. Always try switching cables first. They go bad. People often ask me, how does a cable go bad? I don't know, but they do - I've encountered it many times. Then try different ports, etc. Good luck.