Add to Calendar Link from SharePoint List View Not working

Dear SharePoint gurus-

I am trying to create an "add to calendar" link that will add a Teams meeting / session to a user's calendar from a SharePoint List that I'm displaying as in a custom gallery view. I've been trying lots of ways to do this, with none of them working. Most recently I've tried to implement this https://github.com/pnp/List-Formatting/tree/master/column-samples/generic-scheduling-link from Github but I'm missing something because although the icon display works fine, the h refs/"deep links" that are meant to open Outlook and/or Teams to create events, instead return an error with my list url  plus Invalid%20Date at the end. I'm not totally sure if my problem is in the Formatted Date field, or in the Start and End fields themselves. Also, the "deep links" contain + symbols. Is that an issue?  I've read that it's supposed to contain %20.... I'm feeling totally lost. Can anyone help? This seems like a simple thing but I guess not??