What is the problem?
Octoprint detects and uses C270 webcam if only webcam plugged in, but when another usb cable plugged in (such as to 3d printer main board itself) and the 2nd usb cable isn't connected to anything, just the moment the 2nd usb cable is plugged in, octoprint suddenly stop detecting the webcam (webcam green light disappears)
What did you already try to solve it?
reflash/reinstalled Octoprint on sd card, also played with camera settings in octopi.txt, tried different power supplies
Additional information about your setup (OctoPrint version, OctoPi version, printer, firmware,
serial.log or output on terminal tab, ...)
Here is the weird thing though, I tried another one of my extra raspberry pi's with another octoprint installed on it (for a future 3d printer), and same problem?
all using the newest Octopi 1.3.8
Printer is Tronxy X5s but using another board (MKS gen 1.4)
Not sure if it's octoprint or the raspberry pi, I've tried 3 different pis same issue
On my Cr-10 with Octopi 1.3.5 it works perfectly fine (also using a C270)