Funny you both mention shidehack and vh. I am running some old R808 and a few R606 in my shed. It is only thing I use cgminer at moment. I already tried using vh's fork of cgminer and is doing the same.
I believe it is a problem with Raspbery Pi OS 64-bit when it has more than four sticks. I used my RPi with RetroPie installed as it was closest thing. I had no problem with it recognizing all the Antminer U2.
It has been fun messing with these old stick miners. I held on to two of each stick miner I have ever used. But I think I just uncovered what might be a financial headache in the form of paper wallets. I used these to buy used GPUs 8-10 years ago.

Dont forget that you have to grant access to the USB files after installing CGMiner. (This is assuming that you followed philipma1957 and used VHs fork and default directory from the link that he posted)
cd ~/git/vthoang/cgminer/
sudo usermod -G plugdev -a `whoami`
sudo cp 01-cgminer.rules /etc/udev/rules.d/
sudo reboot
I run this from the ~/git/vthoang/cgminer/ directory:
./cgminer -o stratum+tcp://solo.ckpool.org:3333 -u 1BmcjRJTRQAP7je5B7tDCLw4MDzXceSG9P.0 -p x --anu-freq 250 --suggest-diff 128 --api-listen --api-allow W:127.0.0.1
Keep in mind that you can set the frequency on the U1/U2:
--anu-freq Set AntminerU1/2 frequency in MHz, range 125-500 (default: 250.0)