Amazon has suffered a setback in its bid to open brick-and-mortar retail establishments when Ethereum-like bugs caused the store not to function if more than 20 people were inside at one time. Amazon hoped to roll out the stores, dubbed "Go" at the end of this month, but tests showed that their "shopper-tracking" technology was unable to follow people around the building. Tracking issues reportedly didn't end with just people, as the system also had difficulty locating products that were moved from their original places on a shelf. The stores would not have traditional cashiers, instead letting customers walk in, select items, then have the purchases charged against their Amazon account. The company did not say when, or if, the stores might actually be ready to open any time in the near future.