Immediately after install of second Sierra Beta install, no external USB devices are being recognised. Late 2012 MacBook Pro with two USB3.0 ports.
Seems the devices are found in under System Report/Information through 'About this Mac' and are shown as receiving power output from the MacBook (also device power LEDs are lit, but do not show in Finder and are not accessible in anyway. Non-powered USB devices are also not being recognised.
Have tried an SMC Reset and also a NVRAM reset as suggested in various forum threads but still nothing working. MacBook also has an SD Card port and this works fine when a card is inserted. Also tried basic system restarts and shut downs with and without devices plugged in.
All help much appreciated as this bug makes it difficult to do quite a lot of things...