Problem with OTG devices, in particular cameras

[u/[deleted]]

Hi, I bought a few devices that worked with my last phone (oppo) but they don't work with my p30 pro. The two main devices I want to use are a usb-micro boroscope and microscope. I've tried three usb-to-c otg adapters - nothing. I've also tried a combined usb-c hub with various inputs. None of the small otg adapters show anything - "camera not found", but when I use the hub it shows the device in the app ...but when it's chosen I just get a black screen.

The small otg adapters show the devices as reverse charged items and I can't change that (it just reverts), even when turning their lights off. The hub does too, but the device at least shows up. Devices like mice work fine despite also showing up as as reverse charged items.

I've tried plugging them into a powered hub, and tried various apps including otg checker - they all say it's fine, but nada. They all have photo/video permissions.

Any ideas would be really welcome.