Sorry I meant to say that I can't find the "Share" option my Garmin Connect phone app. I still can share when I'm on my Windows 10 computer like you example shows, but I used to be able to share an activity using my phone.
What phone? iPhone, Android, Windows? This is the Garmin Connect forum, so the assumption is that your are having issues with connect.garmin.com. Here's a thread on the Garmin Connect Moble - Windows forum
Sorry I posted this thread in the wrong section. I finally figured out how to share. I have a Samsung S6 phone and the Garmin Connect app share icon was moved from the upper right hand corner drop down list to a new icon (3 dots connected by two lines) near the center (please refer to the attachment).