I'm running the latest stable build of GrapheneOS on a Pixel 6.
I have just attempted to connect a USB flash drive to the phone using an OTG cable to perform a backup. The OTG cable is this Anker one and the flash drive is a SanDisk Extreme USB 3.0.
When the cable and drive are connected, GrapheneOS displays a notification saying "Charging connected device via USB". When I open this notification, the USB preferences are shown indicating "USB controlled by Connected device". Attempting to switch it to "This device" fails after a few seconds. The USB drive does not show up in the Files app, or as a device in the Backup settings.
On an older Motorola Moto G6 phone, the same OTG cable and USB flash drive are detected immediately, with the storage showing in the files app. If I swap the flash drive for a Logitech Unifying receiver, I can control the phone with a keyboard and mouse. On the Pixel 6, the unifying receiver is also not detected.
Under GrapheneOS, the 'Security -> USB accessories' setting is set to 'Allow new USB peripherals when unlocked'.
Can anyone suggest what the problem might be?