**Bug introduced in 8.0 or earlier and persisting in 11.2**

Possibly the same bug as [(41706)](https://mathematica.stackexchange.com/q/41706/280).

---

Take a look at the first two points on the chart:

```
ListLinePlot[{15, 30, 32, 33, 34, 35}, Mesh -> All]

```

[![ListLinePlot output](https://i.stack.imgur.com/YY8rt.png)](https://i.stack.imgur.com/YY8rt.png)

I have just notified support about this (CASE:3539237), but I wanted to share it with the community.

**Update 2017-08-31**: The bug seems to be back in version 11.1