What you described will happen if you select the icon on the location I noted on my previous post, to add a new icon you have to choose from a different location B4A will copy it to that location posted before, maybe that's your problem.
my problem was that when I tried the "put the file in a different folder" I use the same name as the readonly file (png) I have in drawable for other purposes and it failed to copy it over the read onlyfile