Unable to get USB file transfer working on Oreo 8.1
Based on Izzy's questions, here's what worked for me:  With device plugged in, swipe down to open the notification area.  Tap on "Charging".  Select "File transfer".  Choose "Just Once" or "Always" depending on your situation.  The PC will ask you what you want to do.  I have it open in Windows Explorer and I browse from there.  Hope this helps.  Thanks Izzy  for the pointer.