Keynote or entire keynote legend does not appear on sheet

[gregb]

My office has recently been having problems with individual keynotes not appearing in the keynote legend and just yesterday I was shown a sheet on which the entire keynote legend was empty. The keynotes appear in the views on the sheets. The keynote legend initially shows the keynote number and related text but at some point the legend goes blank. It's not project wide and it doesn't appear to be consistent with particular views or sheets. This looks to be happening in both 2017 and 2018. Thoughts?

[david_peterson]

I've seen that happen as well. Typically I've seen it where a keynote was there and then deleted or hidden in the view, or the Annotation crop changed.
I wish I had a perfect solution for you. The only thing I've ever done was to just remove the legend and place a new one. That seems to be the fix.
But as you mentioned it's totally random and I could never pin point and exact cause.