Thanks for your reply.
As the extension otherwise works fine, my workaround for now is to visit the site https://emojipedia.org, search for and select an emoji there, and copy paste it into the map marker field.
Have you been able to find a solution to get the icon picker working?
I may have a similar problem.
When adding a field for the map marker and try to use the "pick emoji" button, the site reloads, but I cannot select any emojis. Similar behavior happens when I try to select an emoji when creating/editing a content.
When clicking on the "pick emoji" button, the site reloads, but I cannot select anything.
However, when adding a character as default map marker it is shown on the map. So the map marker seems to work, only I cannot pick any emojis.
I don't see any errors in the drupal log or in the browser console.
Thanks for setting up the branch, this way I was able to upgrade.
Only one error: In the file drupal8_zymphonies_theme.theme, in Line 264 there should be a different bracket:
"]" instead of ")"
Otherwise the theme doesn't work.