Hover not working on charts with Date x-axis


I am trying to synchronize two graphs (heatmap and line), both having the x-axis as a Date. If the user goes on the heatmap, the crosshair of the heatmap should trigger (or hover) the croshair of the line chart. I had success by representing the date as a string, but once the date is formatted as ‘yyyy-mm-dd HH:MM:ss’, the hover in the line chart does not respond, nor errors are being thrown.

This is the pen representing the issue: Codepen

Any help will be highly appreciated.

Thank you.