I've been having this issue for months now, but it's been conflated with problems on my (relatively new) Air where it suddenly doesn't like making a decent wifi connection (too much to explain in this thread), and all sorts of strange behaviors in Mail ("ghost" drafts and other messages, lost of stuff that indicates that when Mail goes to the Cloud, it faces and creates all manner of data conflicts). But this text replacement thing is a HUGE problem. Granted, I did create some shortcuts that have themselves been problems, but not being able to control the dictionary of shortcuts is a nightmare. They have invaded all my devices, including my Air.
Still, when I searched to see if anyone else was having such problems, for months, I found nothing. (What? Was the conversation being subverted somehow?) Until finding this today. Small comfort.
After countless, lengthy sessions with Apple at Genius Bars and by phone, no one has been anything other than puzzled. Deer in the headlights. No one at Apple has done anything like admit that there is a systemic issue, not even to say that others have reported same. Amazing.
Reading through the thread, I don't even have to think about the attempted solutions, hacking or otherwise, because I can tell you they won't work. They won't stick. Somehow, somewhere, some "ghost" backup is being made against a user's Apple ID that retains these text shortcut files, and nothing that can be done at the user level is going to stop that. They will come back, like zombies. This problem is in the Apple Cloud. Period. Somehow, somewhere, whatever "backups" Apple keeps of OS user data are retaining this date on an individual user -- even if we delete our own backups (tried that) -- and it seeps back.
I have a new iP6, the relatively new Air, and an 2012 iPad Mini, and I keep everything up to date, so it's nearly impossible for me to tell if this sources to iOS8 or some interim update. The only thing I have been able to do is clear the ****** things off my Air, and they appear to be staying away, even though after all sorts of cleaning (everything short of dousing the phone and iPad with kerosene and setting a match), they have crept back on the iOS devices. Will report on whether they stay off the Air, but I intend to avoid hardwiring the phone to it until I see what happens, in case that's involved.
But all I have been told (just today) is that Apple is working on a "patch."
sigh...