Question

This is done by using a Firewire 400 to 800 adapter, then Firewire 800 to thunderbolt, then thunderbolt 2 to Thunderbolt 3(USB C) adapter.

Answer 1

Double check that your port is Thunderbolt 3 and not just USB-C. It'll have a little lightning bolt next to the port.

If it IS thunderbolt there could be some thing blocking communication. Create a support ticket, they should be able to help you out.

https://support.presonus.com/hc/en-us/articles/210050813-How-to-create-a-new-Support-Request-