When Elon Musk announced last fall that all of Tesla’s cars would be capable of “full autonomy,” engineers who were working on the suite of self-driving features, known as Autopilot, did not believe the system was ready to safely control a car, according to the Wall Street Journal.

The WSJ report sheds more light on the tension that exists between the Autopilot team and Musk. CNN previously reported in July that Musk “brushed aside certain concerns as negligible compared to Autopilot's overall lifesaving potential,” and that employees who worked on Autopilot “struggled” to make the same reconciliation.

Some employees have left Tesla over the way the company markets Autopilot

A major cause of this conflict has apparently been the way Musk chose to market Autopilot. The decision to refer to Autopilot as a “full self-driving” solution — language that makes multiple appearances on the company’s website, especially during the process of ordering a car — was the spark for multiple departures, including Sterling Anderson, who was in charge of the Autopilot team during last year’s announcement. Anderson left the company two months later, and was hit with a lawsuit from Tesla that alleged breach of contract, employee poaching, and theft of data related to Autopilot, though the suit was eventually settled.

A year before that, a lead engineer warned the company that Autopilot wasn’t ready to be released shortly before the original rollout. Evan Nakano, the senior system design and architecture engineer at the time, wrote that development of Autopilot was based on “reckless decision making that has potentially put customer lives at risk,” according to documents obtained by the WSJ.

When reached for comment, a Tesla spokesperson referred back to the company website, where a disclaimer for Autopilot reads that “self-driving functionality is dependent upon extensive software validation and regulatory approval.”

In between those two particular inflection points mentioned in the report, a driver died while using Autopilot for the first time. Last summer, 40-year-old Joshua Brown’s Model S collided with an 18-wheeler on a Florida highway, killing him instantly. In January of this year, an investigation by the National Highway Traffic Safety Administration found no defects in the Autopilot system, and that the feature dropped crash rates by 40 percent. Meanwhile, the US National Transportation Safety Board is set to vote on the cause of the crash in September.

Update August 24th, 4:53PM ET: Added comment from Tesla.