Tooltip sometimes doesn't display

[Rasie1]

Configuration

System: Manjaro, i3, xfce4-panel Version: 1.5.2

Steps to reproduce

1. Hover mouse over widget
2. Tooltip popup display is expected, but is not shown

Additional details

All other tooltips work but multiload-ng's.

If you continue to move your mouse between indicators, tooltips will start working eventually: only after second indicator is hovered. If there is only one indicator on panel, you can't see the popup (which is specifically annoying because I put battery indicator separately). It also sometimes just works (maybe depending on app you're hovering from?)