A critical advisory group on regulating the commercial uses of drones failed to reach a consensus on recommended security safeguards, likely hampering the development of the U.S. market for using larger remote piloted aircraft.
The group of about 70 industry and law enforcement experts reported to the Federal Aviation Administration earlier this month that it split over what types of drones should be subject to tracking requirements, the Wall Street Journal reported. The report has not been made public.
Companies are already using the unmanned aircraft to perform all sorts of tasks, ranging from inspecting cell phone towers to photographing fields of crops. After the recent hurricanes, the FAA allowed drones to be used to survey the damage and help track assignments of first responders.
But many broader uses, like package delivery, are being held up until the FAA issues more rules and drones have also been caught being used by drug dealers and, in rare instances, interfering with larger, manned aircraft.
FAA chief administrator Michael Huerta, who heads the agency, said last month that the advisory group’s recommendations were needed to guide future rule making efforts. “I can’t stress how important this work is,” Huerta said in a speech in Las Vegas at the InterDrone conference. Acknowledging disagreements within the group, Huerta sounded optimistic at the time, saying that “tension between different interests and perspectives helps bring us all to the middle, creating the right balance.”
Get Data Sheet, Fortune’s technology newsletter.
A majority of the advisory committee agreed that existing or soon to be developed technology could be used to detect and track even small drones. But members could not agree whether tracking requirements should apply only to larger, more capable devices, to all drones regardless of size, or to most aircraft excluding only smaller hobbyist drones, the Journal reported.
Fortune asked the FAA for comment and will update this story if a response is received.
The FAA had draft tracking rules ready last year but the FBI and other security agencies in the government objected, prompting the formation of the advisory group. The FAA did issue rules governing some commercial uses for drones in August, 2016, but still required case-by-case waivers in many instances, such as flying the remote piloted aircraft beyond the line of sight of the operator. Companies like Amazon (amzn) and Google (googl) are interested in using drones for remote delivery, wireless connectivity, and other business opportunities, but are stuck in testing phases without clearer rules.
The number of hobbyist drone owners is forecast to triple to 3.6 million by 2021, while number of commercial users will increase 10-fold to almost 500,000, the FAA said earlier this year.