I was trying to connect a computer-based USB-C port to a MIDI keyboard earlier in the year and discovered something that frankly shocked me: once the cord length is greater than 6 feet, the data connection utterly fails.
I tried several different cables (I really wanted a 15-to-20 foot cord... simply for reasons of geography in my workspace), but they all failed to deliver data between the computer and the MIDI board. Only when I got to 6 feet did it work.
Mind you, if all you need to do is charge a device with USB-C, then you’re fine... 10 feet, 20 feet... no problem. Also, USB-A (with lower USB protocol versions) also work at longer lengths. But not USB-C and definitely not at the faster data speeds of USB2.0 and USB2.1 or higher.
(Oh, one more thing: I did buy a PCI-bus card to give me dedicated USB-C ports on the computer... didn’t help: it was all about the cable lengths vs. the data rates.
I like the Yellow bus. Don’t we all love the yellow bus??
I believe you can get USB-C cables with signal boosters. The MIDI probably doesn’t have enough juice, the PC is probably fine. I’ve regularly used 12’, 18’ and 20’ USB-C cables to connect 4k 60fps cameras for event streams without problems.
Get a long USB cord which has a built in repeater. I'm running a ~15 ft long one from my Vdrum's usb midi connection to the workstation in my recording studio. Works flawlessly.
I’m going to take a guess that the longer cables need to have lower capacitive and inductive losses per foot than a 6 foot cable. So you are likely talking about a quite bulky cable compared to the usual. Very crudely it’s analogous to “in the old days” I had a long run of RG-6 coax to my outside FM antenna. Replacing the original RG-59, the RG-6 definitely made a difference when I was trying to pick up KSHE in St. Louis!