ggiraph sometimes displays factor values - supposed to display factor labels

[smithjd]

I like the way the ggiraph package works on my Quarto site, but I'm seeing a strange anomaly.

Here is a snapshot when it's working correctly when I hover over one dot:

But an adjacent point displays the factor number rather than the label when I hover over a nearby dot:

Any ideas how to investigate this? It seems like a black box to me. Looking at the data frame and the ggplot code does not suggest anything. (Apologies, because creating a reprex of this plot seems a bit daunting to me.)