[Bug] If selected series has null value, the tooltip doesn't show with showTip dispatchAction

[petercsaki]

Version

5.6.0

Link to Minimal Reproduction

https://codepen.io/petercsaki/pen/jEOWgre?editors=0010

Steps to Reproduce

1. Create a chart with multiple series, where one has null values. Enable tooltips for it.
2. Trigger the tooltip with dispatchAction showTip, with the seriesIndex pointing to the series that has null value.

Current Behavior

The tooltip doesn't show at all.

Expected Behavior

The tooltip should show.

Environment

- OS: any
- Browser: any
- Framework: none

Any additional comments?

When the selected series has a non null value, the tooltip shows, even if other series have nulls.
The same problem was fixed in 5.3 for the normal, hover over tooltips. #15757 The event driven tooltip was not fixed back then.

[helgasoft]

Workaround is to add an invisible series without missing values first, then tooltip dispatch will work.
Of course the tooltip content has to be customized - Demo.