Firefox only: hovertext bounding box in heatmap chart is not always correct

Just wondering, is it a known bug that hover text in heatmap chart sometimes appears without background? More precisely, the svg path for hover text container is not calculated correctly: d=“M0,0L6,6v-3h6v-6H6V-6Z”, and appears as a small arrow, see below:

When displayed correctly, it looks like this:

The bug appears in Firefox only (using FF 55.0.3 on Mac OSX with plotly 1.28.2), It does not show in Chrome or Safari. Please, let me know if you’ve seen this bug before or know what might be causing it?

Thanks for the report.

Can you share a reproducible example our your graph to help us debug?

Codepen with two heatmaps

Notice that in Firefox, the hover text shows up fine in the first heatmap, but not in the second. Also notice, that in the second heatmap “longer tooltip 3” appears on the right.

Ok thanks @tgoldina, you can subscribe to for the most up-to-date development info.