I found that a map I created with href in the tooltip was not working today. After trying 3 browsers on my Mac and a re-boot, I switched to Linux and found the same thing. So, I checked the Altair example that it was based on here:
https://altair-viz.github.io/gallery/scatter_href.html
And this also does not work for me. The Tooltip dialogue appears normally but the html link is not active. I did notice at first it worked when I tried on a Linux machine (in Chrome but not Firefox) but after clearing my cache in Chrome it also stopped working. The Altair example also is not functional on a different Mac. I’ve never had any problems with this before--- even worked on a iPad. So, I’m curious what might explain this loss of critical functionality. I realize this might not directly be an Altair issue but maybe related to Vega-lite or javascript, but I’m not knowledgeable about these at all.
This is due to a bug in Vega 5.12.1. If you render your chart with a different Vega version, it will work. See https://github.com/vega/vega/issues/2641 for more information.