hmmm... do you know how to get into your developer mode? my girl had this issue on her S8 and it ended up being that she had plugged it into her car and it got stuck in the navi and music playback. Didnt matter how many times she plugged it into the computer it was reading that it was set to transfer files but it wasnt really. I can lead you through the steps and it might solve the problem
We want to head into Settings>About Phone>Software Information>Build Number(begin clicking on this until your phone splashes a banner saying you've entered Developers Mode).
From here we will want to go back into Settings and scroll to the bottom where you should find Developers Mode.
Enter here and scroll down until You find your USB Configuration Settings. Inside there you will be able to manually change them. Also above the USB configuration section you will find a USB Hardware Acceleration. Go ahead and turn it on (this helped finding the device correctly when our Chromebook Updated) Try plugging in your device and switching between configurations.
there are multiple ways to connect, and use connections, for doing multiple things; all of those will do more then one direct thing. (charge your device, clone, transfer files, tethered share, tethering Hotspot, etc...) If your having trouble transferring files, I might suggest that you try and offload/download your phone via reboot to download mode and see if that works for you. You posted your laptop has proper drivers and things so if it downloads right at least you'd have transfered what you've been wanting to and can sort through the rest. If you haven't download smart switch on your laptop then you should and can then create a back up of your phone just in case you ever need one.