When a buyer purchases an item from Facebook Marketplace, Facebook holds the funds until the item has been delivered, and then releases the funds to the seller within 5 days. However, some people have not received their money after 3 months of waiting. Others have said that they never received the money from Facebook. Facebook is holding over $10,000 from one Facebook Marketplace seller.
In response to the complaints, customers only receive automated messages from Facebook encouraging them to keep waiting. There is a similar lawsuit against eBay and Paypal for fraudulently holding sellers funds.