The script removed all the time different legend entries, very randomly, also with the code from Aftaloon, but after endless attempts I found a solution.
I removed the legend and placed it back



ochart.Legend.Delete
ochart.SetElement (msoElementLegendRight)


With ochart.Legend.LegendEntries
For z = .Count - NumberOfSeries To NumberOfSeries + 1 Step -1
.Item(z).Delete
Next
End With


Now only the right legend entries are removed when I press my refresh button. I think some entries were not yet made before the removing started? Is that even possible?

I hope this helps some other people struggling with this in the future.