Tooltip bug on custom series

### Version
5.0.2

### Reproduction link
[https://jsfiddle.net/kbztor76/](https://jsfiddle.net/kbztor76/1/)

### Steps to reproduce
1. Use provided example (with option 'trigger: axis' for tooltip)
2. Slide along one bar by mouse
3. In the middle of the bar, the tooltip changes and shows info from the next bar

### What is expected?
Should show correct info in tooltip

### What is actually happening?
Tooltip shows info from the next bar