When I start ArcMap after installing my add-in successfully (built with ArcObjects 10.4 .NET SDK), I see the add-in's toolbar and I can see it in the list of Extensions, but it does not show up in the Add-In Manager. And the add-in does not seem to have been loaded properly (add-in has problems when you try to use it). However, if I just restart ArcMap, then everything works fine, i.e., it shows up in the Add-In Manager, and the add-in works properly.
