Everyone's heard the warning "buyer beware," but sellers face their own pitfalls when using online marketplaces — as one Massachusetts man learned recently.

Keith Mackenzie-Betty recently sold his 2014 Toyota Tundra on eBay for $23,750. According to CBS Boston, he'd only received $11,625 in payment when the online marketplace told him he could hand over the truck to the buyer.

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"I said, 'Hang on, I've only had half my money,'" Mackenzie-Betty told the outlet. "Who parts with something when they've not been paid in full?"

The buyer, however, paid the full amount, and Mackenzie-Betty says eBay gave him the green light to hand over the truck.

But then, he says, eBay followed up to say they'd made a mistake and needed him to provide the car's title or, as Mackenzie-Betty put it, "You're not getting paid your other half of the money."

The buyer paid — so why isn't the money in your account?

Mackenzie-Betty, as a result, reached out to CBS Boston — which contacted eBay and learned that they "worked directly with the individual to resolve the matter."

An eBay spokesperson told Moneywise that "trust is foundational" to their marketplace and explained that "There was a miscommunication regarding the title transfer process because the buyer had selected a service that included title and registration processing."

They said that once the seller notified them, "Our team quickly verified the transaction with the buyer and issued the remaining payment the following morning," adding that they're "reviewing the experience to help ensure guidance is clear and consistent going forward."

Meanwhile, Mike Danford, co-owner and Chief Strategy Officer at Adverio — an omni-marketplace operator group that works with e-commerce brands like Amazon and Walmart — says that an issue like this one is not specific to eBay.

"It's how most every marketplace is built," Danford told Moneywise. He described online marketplace platforms as "effectively escrow accounts" that "optimize for buyer protection, not the seller's cash flow."

"On a marketplace, you don't get paid when the buyer pays," he added. "You get paid when the platform decides its risk has cleared enough to send the seller the money."