Multiple sellers told CNBC on Thursday that the back-end system for tracking orders and sales has been down since Wednesday afternoon. Although it's still recording customer orders, sellers are unable to access their daily sales numbers to see what products they're selling or how much they're making.
Amazon has been unresponsive so far, the sellers said, only addressing the issue through the following statement posted in a seller forum: "Technical Notification — We are currently experiencing a system issue that is impacting Business Reports."
Amazon didn't immediately respond to a request for comment.
The company known for managing some of the world's most sophisticated technical infrastructure has experienced a number of glitches of late. On Wednesday, thousands of customers complained about Amazon's search bar malfunctioning, mostly in the U.S. market. In July, Amazon also suffered a major crash for hours during Prime Day, one of its biggest sales days of the year.
Although accounting mistakes aren't uncommon for sellers, an outage of this magnitude is rare. It's not clear how the issue will affect sales, but sellers are already expressing concern that without access to their daily metrics, it's impossible to make future business plans, like determining how much inventory they need to buy.
"Without knowing how many of an item I sold, I don't know what to reorder," said one seller, who asked to remain anonymous due to privacy issues. "If we are even a day or two late in reordering product, we can go out of stock and literally kill a top-selling product."
Third-party sales now make up more than half of all e-commerce volume across Amazon's sites.