From the mobile app I added a new pair of shoes, and retired another pair. The pair that I retired are still visible in the list, in italics, whereas my previously retired shoes are not. Somehow gear retired from the mobile app are not treated equally as gear retired from the web-version. This is pure discrimination!
In addition, and the biggest problem; the new pair of shoes that I added are NOT visible in the list, so I can't select it from the app.
As ASmugDill stated in this thread: https://forums.garmin.com/forum/into-sports/garmin-connect-mobile-application/garmin-connect-mobile-android/127913-retired-gear-still-appear-on-list Garmin Connect Online does things right and made it possible for me to select the right gear, and once again retire the retired pair. This makes it even clearer that the app is the problem, not the back-end.
But, adding and retiring gear from android app is useless.