I have also encountered this same issue with both the AT&T HTC One and the Developer Edition of the phone. I've actually notified 2 different HTC contacts that have been participating in a discussion about the HTC One on Reddit. You can find the discussion here: Hello from HTC : Android
EDIT: (If you search for my handle, "DisconnectedChild", that will take you to the relevant posts in the Reddit thread).
One of them already got some of the HTC engineers to reply to this issue but it's still ongoing because they didn't seem to try using any third party apps that have an accessibility component, like the Pebble app or Light Flow. Hopefully they'll continue to follow up on this and issue an update to fix it.
Yeah, it is definitely the Pebble app for me. Once accessibility is turned on, the screen becomes single touch for shortcuts and otherwise. I really hope they fix this issue, because I like the drag to unlock and I obviously want to continue using my Pebble.