DFR0845 UART to RS485 Converter 12V supply issue

I have hooked up the DFR0845 per the diagram provided in the datasheet, but as soon as I connect the 12V+ from the power supply (limited to 0.180A) to the 12V IN terminal, it causes the Arduino to disconnect from my computer.  I tried the same setup with an RPi Pico 2 W and something similar happens: Windows reports a power surge on the USB device and says the device needs more power than the USB port can supply.  Why is this happening if the 12V / RS485 side is isolated from the UART side?  Is the device defective?