So I also had this issue with the USB not mounting in 10.0.1. I reinstalled the VM Ware tools and restarted the VM. Nothing. Then I went into system preferences and allowed what High Sierra blocked, while I still had my guest open. I shut it off, closed Fusion, opened it back up and started the guest. USB mounting now works. YMMV
I have exactly the same problem. Upgraded to High Sierra and to Fusion 10. My USB stick is mounted to MAC OS and no question is coming to select between Mac OS or Windows.
ghostface147, what do you mean with ".. and allowed what High Sierra blocked"? I cannot find anything under system prefs relating to High Sierra blocking Fusion/Windows.
Not sure exactly when I lost USB but needed it today and would not mount. I've been on High Sierra 10.13.2 and recently upgraded to Fusion 10.1.1. Since you mentioned the Security & Privacy, I had it open and the moment I selected Install VMWare Tools and Modify, Allow appeared and I selected it. Once Tools finished installing, I started Windows, plugged a thumb drive in and POW, the window asking if I wanted to mount USB on Mac or Windows popped up and was able to mount it. Thanks for the tip!