Page 4 of LP's manufacturer installation instructions clearly show the use of the "Z" flashing as previously mentioned by Mark. It doesn't appear that any flashing was used, particularly because the Horizontal Wall Joint detail requires a 3/8" gap between panels which would be more noticeable.

The Horizontal Bandboard detail for multi-story buildings on page 5 shows the same 3/8" gap above the bandboard with the Z flashing covering the top of the bandboard.

No where does LP offer "Flash, caulk, fill, sand, paint" as a proper detail.

If there is no Z flashing, this is a future rot fest. A tight butt joint with caulk is no flashing substitute. The proper solution is to remove all the siding with the joints and replace it with continuous siding as shown to be possible by the continuous siding of the same length immediately left of the window.

And what is the fine line in the siding immediately below the window please? It appears to be another unflashed butt joint. If so, that's gotta go too. Looks like these guys were trying to use remnants to finish this job. This level of cluelessness would make me compare the entire installation to the manufacturer's installation instructions.