I'm having the same issue, and I have urgent needs to get a project rolling by tomorrow. Could someone please contact me directly about this, and what we can do? Thank you!
Please note that Upwork is an online marketplace, through which users can connect to enter directly into service relationships. Through the marketplace, clients directly engage and pay freelancers to perform services. Upwork acts as an escrow agent and passes funds from the client to the freelancer. That's why we don't believe a W-9 is necessary. Upwork provides 1099-Ks if appropriate to freelancers if certain conditions are met. More information is available here.
I will have a member of the Customer Support team reach out to you to assist you with your request. Thank you.