Security company Allied Universal warned Anthropic that its workers might go on strike, prompting the AI company to order its staff to work from home, but the security guards’ union said it knew nothing about the strike.

Anthropic told employees at its San Francisco offices to stay home Monday and Tuesday after receiving notice from its security contractor, Allied Universal, that its workers could potentially walk off the job, as Business Insider reports. The Service Employees International Union (SEIU), which represents many of the security workers, told the outlet it had neither authorized a strike nor threatened one for this week.

The union reportedly said it has been engaged in lengthy contract negotiations with Allied and other California security companies since April. The union represents thousands of security workers statewide and is seeking higher wages, improved healthcare benefits, and more extensive job training.

Neither company responded to requests for comment.

According to Business Insider, Anthropic generally requires employees to work from its offices at least 25% of the time under its hybrid policy. Security concerns have also become an increasingly prominent issue across the tech industry, with The Wall Street Journal reporting threats against employees at both Anthropic and OpenAI.

The timing comes as Anthropic prepares for a potential initial public offering. The company made a confidential filing in June and could file publicly as soon as August, while secondary-market trading has reportedly pushed its valuation to about $1.5 trillion.

Allied Universal has also faced scrutiny in recent years. Oaklandside reported last year that the City of Oakland withdrew a proposed contract with the company after it was revealed that one of its subsidiaries works with US Immigration and Customs Enforcement. The city also found what it described as a “shocking” number of lawsuits and violations involving Allied.

Earlier this month, Allied became the subject of a lawsuit over the theft of two shipping containers holding about $858,000 worth of merchandise from a Mercedes-Benz facility in Fontana, California, while the property was under the company’s guards’ watch. The complaint alleges that the guards failed to properly monitor surveillance footage, detect unauthorized vehicles entering the property, patrol the facility, or control access to the site.

Related: Like OpenAI, Anthropic Makes SEC Filing Ahead of Possible IPO