Garmin Jr. missing mutual connection from Add Participants screen

I have Garmin Jr. setup with myself (family admin), partner (family guardian), and young child (using Vivofit Jr 2).  Now I also have an older child (with a Vivoactive 3).  The older child is a mutual connection for both myself and my partner in Garmin Connect. I want to add the older child to a challenge, but, in the Garmin Jr app:

  • if I go to "... More" -> "Family" -> "Connections", the older child is listed there.  And if I click on to them, it shows "2 Connections - 1 Mutual", where those two connections are partner and myself.  So all good, and as expected there.
  • if I go to "Challenges" -> "Daily Steps Challenge" -> (top right menu button) -> "Add or Remove Participants", I get a screen stating "Your Connections Will Be Listed Here Mutual connections of the family administrator and the family guardian can be added to the leaderboard. Manage connections in Garmin Connect."

Clearly this is broken (no surprise, Garmin software breaks all the time). Any tips or suggestions to un-break it?  The older child's Connect profile is sharing steps with us (I can see their steps in Garmin Connect).  I've cleared the apps data.  I've un-installed and re-installed Garmin Jr. Nothing has helped.

To add to the weirdness / brokeness, the first time I went into the "Add or Remove Participants" page, the child was listed there and I added them.  They appeared briefly (a few seconds at most) on the leaderboard, then disappeared.  I've not been able to add them since.

Any suggestions? (Besides wait, and Garmin will probably fix whatever's broken on their end in a few days / weeks... which is probably what will happen in the end).