Apple doesn't know why iTunes users' music files are disappearing

Apple late last week acknowledged iTunes users who claim the software deleted their music files, saying it will issue an update to iTunes next week that includes additional safeguards. The company confirmed, in a statement given to iMore, that "in an extremely small number of cases, users have reported that music files saved on their computer were removed without their permission." However, Apple was unable to reproduce the bug, indicating it doesn't really know what's going on here.

The issue, which has persisted since the launch of Apple Music last year, resurfaced when iTunes user James Pinkstone published a blog post last week titled, "Apple Music stole my music. No, seriously." The post, which went viral, detailed how Pinkstone's library of 122GB of music suddenly disappeared. He was allegedly told by an Apple representative that his files were deleted without his permission when he signed up for Apple Music. Pinkstone says the Apple rep told him Apple Music replaced his songs with cloud-based versions from its digital collection, deleting the originals in the process.

Apple apparently walked back those statements in a follow-up phone call to Pinkstone. The company's full statement today also makes clear that file deletion is not an intended function of the company's streaming service:

In an extremely small number of cases users have reported that music files saved on their computer were removed without their permission. We're taking these reports seriously as we know how important music is to our customers and our teams are focused on identifying the cause. We have not been able to reproduce this issue, however, we're releasing an update to iTunes early next week which includes additional safeguards. If a user experiences this issue they should contact AppleCare.

We still don't know what's causing the problem, as it doesn't appear to be simply user error or oversight. iMore notes how the bug could originate with Apple's confusing Cloud Music Library feature, which is designed to let you listen to songs on devices that don't contain the original files, like an iPhone or, say, the Mac you use for work. The whole process gets particularly wonky when it begins to mingle with other cloud services like Apple Music, which iMore says may be the source of the problem if you're using iTunes version 12.3.3. Apple won't say right now.
So until Apple figures this out, it's probably safer not to mix a carefully curated collection of MP3s with a cloud-based library known for being less-than-stellar at file management. And create backups, if you can.