Hello Luccatiel,
I have the same issue connecting the radios via USB and the radios led did not turn on. I tried connecting the radios to my laptop and they work fine. I have changed the radios and the problem persist.
A related problem with radio communication was posted last year here> Base and rover connection with radios does not work - #5 by Franz_Helmli
and here> Reach can't find 3DR radio connected via USB OTG - #15 by mikhail.avkhimenia
In that post, there was a problem that apparently has been solved in the latest version. But I can not tell since I haven’ t tried it yet.
One possible solution is changing the radio to the DF13 ports as shown in this video posted by Dennis Baldwin> Reach RTK GPS Long Range Setup w/ 915 MHz 3DR Radios - YouTube
Let us know how it goes.