From the comments in MBS-13235:

hey! there seems to be an issue with the cleanup for links with an underscore. for example, https://www.livenation.com/event/1A_Zkv-Gketafdb/ cleans up to https://www.livenation.com/event/1A, which just leads to an error page. because of this, i can't add the actual link to this event.