Realist wrote:
Forgot to mention that the mount is 5 inches from the ceiling.

Andy comments:

Usually the wiring is run thru the attic to the room, where it
goes DOWN the side of a stud. Then, it is often carried to the
other room outlets at the outlet height, around 15 inches or so from
the floor. Windows and doors mean going back up a stud....

So, you "might" have hit the wire rwhere it runs up or down a
stud.
Statistically, it is very rare,.... but it is possible.

Good luck.