Chicken nugget woes are apparently expanding at McDonald’s Japan outlets, as the chain has admitted another incident in which an inedible object was found in a nugget, this time at a shop in Tokyo, NHK and other media reported Tuesday.

According to the fast-food giant, the latest case was reported on Dec. 31 from an outlet in Koto Ward, Tokyo, after a customer who had bought chicken nuggets complained that a foreign object about 5 mm long that looked like a piece of vinyl was in one of them, the reports said.

However, an employee who received the claim lost the vinyl piece in question while trying to place it on a tissue paper and move it, and the outlet reported the problem to the company headquarters five days later, the reports said. This is making it difficult to track down the circumstances regarding how the object got into the product, according to the reports.

The latest incident comes on the heels of a similar case in Misawa, Aomori Prefecture, in which a foreign object was found in a nugget sourced from a Thai company.

McDonald’s Japan had switched nugget suppliers to the Thai firm after a previous food scare involving the Chinese firm Shanghai Husi Food Co. made headlines last year.

At that time, video footage showing plant workers picking up and recycling meat that fell onto the factory floor and mixing out-of-date meat with fresh product went viral.

McDonald’s Japan is investigating a possible link between the cases in Aomori and Tokyo, but officials were quoted as saying they have yet to determine where the nuggets were produced.