Last week, we drew attention to a blog post from James Pinkstone in which he described how iTunes Match deleted 122GB of his personal music collection went viral. Apple confirmed the issue on Friday and rolled out a potential fix with iTunes 12.4 yesterday, but Pinkstone today has shared a new blog post detailing the extreme lengths to which Apple went in order to track down what exactly caused the problem in the first place.

Pinkstone today wrote that Apple sent two engineers, named Tom and Ezra, to his home to investigate the issue and attempt to recreate it. The two Apple engineers apparently spent “most of Saturday” working with Pinkstone and various other engineers via conference calls in an effort to recreate the problem.

The Apple engineers hooked up an external hard drive to Pinkstone’s laptop and ran a specialized version of iTunes trying to recreate the mass deletion of music. They spent most of Saturday running tests and communicating heavily with Cupertino throughout the process. On Sunday, Tom returned to Pinkstone’s house to collect data of his iTunes and Apple Music usage on Saturday night, hoping to find some correlation between his habits and the deletion of music. But ultimately there was nothing.

Pinkstone says that overall nothing apparent came from the hours the Apple engineers spent troubleshooting at his dining room table, but he noted it’s an odd issue to recreate. He explained that there’s no pattern to the files that were lost. There were various file types and genres all lost with no relation to one another.

After lunch, we spent hours troubleshooting, but the problem eluded us. This time, the files remained, which was just one of many confounding elements of my whole saga. The problem wasn’t cut-and-dry, therefore has proven difficult to replicate. For example, one of the many confusing things about the initial file loss was that only most of my music files had disappeared. Most, but not all. To further muddle the issue, the missing—and remaining—files had little in common; some were WAV, others Mp3, others protected AAC files that I’d purchased when iTunes went through its 2003 through 2009 “controlling boyfriend” phase. Genre, size, and artist name varied greatly among the missing files, as did date added. There was no discernible pattern.

At this point, it’s still relatively unclear as to how effective the iTunes 12.4 update is at solving this issue, but it’s clear that Apple is incredibly dedicated to making sure nothing like this ever happens again. Say what you want about Apple, but I have a hard time believing that any other company would send two senior engineers across the country to help troubleshoot the root cause of an issue.