Bridgy pulls comments and likes from social networks back to your web site. You can also use it to publish your posts to those networks.
When I subsequently remove the emoji from the permalink, and reprocess Bridgy then has no problem finding the URL and sending the webmention. So at least there’s a “fix” on the user’s side for those experiencing this issue, but only if they’re aware it exists and have the means of executing it.
Example of failed webmention:
(I’ll note that it’s also got a fragment # in the URL, but don’t think this is a part of the issue)
Original: https://boffosocko.com/2019/04/29/%F0%9F%93%85-virtual-homebrew-website-club-meetup-on-may-15-2019/?replytocom=262215#respond
Syndicated copy that was liked: https://twitter.com/ChrisAldrich/status/1129124049068498944#favorited-by-14591484
Bridgy Log: https://brid.gy/log?start_time=1558056830&key=aglzfmJyaWQtZ3lyTAsSCFJlc3BvbnNlIj50YWc6dHdpdHRlci5jb20sMjAxMzoxMTI5MTI0MDQ5MDY4NDk4OTQ0X2Zhdm9yaXRlZF9ieV8xNDU5MTQ4NAw
Example of previously failed webmention that ultimately went through following emoji removal:
Original: https://boffosocko.com/2019/04/29/%F0%9F%93%85-virtual-homebrew-website-club-meetup-on-may-15-2019/?replytocom=262215#respond
Syndicated copy: https://twitter.com/ChrisAldrich/status/1129124049068498944#favorited-by-19844672
Bridgy Log: https://brid.gy/log?start_time=1558714459&key=aglzfmJyaWQtZ3lyTAsSCFJlc3BvbnNlIj50YWc6dHdpdHRlci5jb20sMjAxMzoxMTI5MTI0MDQ5MDY4NDk4OTQ0X2Zhdm9yaXRlZF9ieV8xOTg0NDY3Mgw
Another potential example from Instagram
Done via PESOS from Instagram which I’m sure missed webmentions (though too far back to find the specific logs):
https://boffosocko.com/2017/10/15/docteur-jerry-et-mister-love-%E2%9D%A4%EF%B8%8F%E2%9A%97%EF%B8%8F%F0%9F%91%93%F0%9F%8E%ACi-found-this-original-french-one-sheet-47-x-63-after-the-move-will-have-to-get-it-mounted-and-fram/