The first invasive brain chip that Neuralink embedded into a human brain has malfunctioned, with neuron-surveilling threads appearing to have become dislodged from the participant’s brain, the company revealed in a blog post Wednesday.

It’s unclear what caused the threads to become “retracted” from the brain, how many have retracted, or if the displaced threads pose a safety risk. Neuralink, the brain-computer interface startup run by controversial billionaire Elon Musk, did not immediately respond to a request for comment from Ars. The company said in its blog post that the problem began in late February, but it has since been able to compensate for the lost data to some extent by modifying its algorithm.