Less than two years after being slapped hard by the FDA for problems at three plants it got in its buyout of a sterile injectables specialist Agila Specialties, another Mylan plant in India has been issued a warning letter for ongoing data integrity issues.

In the warning letter, issued last week and posted by the FDA today, the agency said investigators continued to find issues with batch testing results disappearing from computers when failed tests were involved. The observations were based on an inspection of the finished pharmaceutical plant in Maharashtra, India.

In a statement today, a Mylan spokesperson said the company was working closely with the FDA to address the issues raised in the warning letter.  “Mylan has always had a deep and unwavering commitment to quality everywhere we operate.”

She noted that the plant is just one of 50 the company has and that the warning letter would not result in any supply disruptions. 

The FDA, however, noted in its warning letter that the plant had been cautioned during an inspection in 2015 about missing data.

It noted that even though the facility invalidated 101 of 139 initial out-of-specification (OOS) assay results, about 72%, employees never thoroughly investigated to find the root cause of the issues and didn’t include them in the results reported to the agency.

“Because your laboratory investigations frequently invalidate initial failures without cause, your laboratory trending excludes a large proportion of data that would otherwise alert you to problems in your laboratory system,” the FDA said, pointing out that the agency has discussed this kind of issue before.  

Further it criticized the quality control lab for not bothering to look into error signals from the HPLC computers indicating loss of data. The lab blamed the problems on power interruptions and computer connectivity problems, but couldn’t explain why they so often happened in the lab and why it didn’t bother to find a root cause.

The agency ordered Mylan to go back and document all of the missing data and figure out what impact those failed tests may have had on its drugs. It said the company needs a corrective action plan to deal with the issue so it is not repeated going forward.

In 2015, the FDA savaged three of the sterile injectables plants that it got in its $1.75 billion buyout of Agila Specialities from India’s Strides Arcolabs. It said it knew the company had only recently acquired them, but pointed out that one had been cited in a warning letter before Mylan bought it, giving the company an indication there might be manufacturing issues that needed to be addressed. Considering Mylan’s extensive experience in generic drugs, the agency said, that should have been enough for the company to get control of problems there as soon as it took over.

Related: Mylan fired workers at Agila plants after getting FDA warning letter

Mylan pledged to do better, but also went after and received from Strides a $70 million payment to help cover the costs.

Problems with data integrity have plagued many Indian drugmakers, like Sun Pharma and Wockhardt, resulting in an avalanche of FDA warning letters in the last few years.

The FDA this year issued a warning letter to a Wockhardt plant in India for issues including data integrity. It followed that up with a warning for a Wockhardt plant in the U.S. that castigated the company for not getting on top of these issues despite ongoing FDA discussions about its problems at other Mylan plants. It pointed out that the warning letter for the U.S. plant was the company’s sixth for seven Wockhardt plants, three of which have been banned from shipping to the U.S.