[1.0] Missing event markers in history tab

[Pangaea]

Don't know what the cause of this is, but it's been a long-standing issue that the 'dots' or event markers in the history tab go missing. I understand this isn't exactly on top of the to-do list, but can you please have a look at it?

Here is one screenshot, that in itself doesn't say much ofc. But we have had 3 or 4 weddings (one very recent), and a good deal more events than is highlighted on top of the chart. I've not noticed a pattern of what goes missing, though. Sometimes ship events don't show up, but at other times they do.