This happens in only one of my two accounts/profiles/users, specifically my regular user. My other account, an administrator account, is not affected by this problem.
I'm on Xubuntu 16.04.2 kernel: 4.4.0-67-generic
I first noticed this about a week ago, maybe a bit more. Applications fail to show up in the panel. The main problem obviously is when the program(s) is/are minimized, in which case I have to go to Task Manager to close it and that's all I can do. There is no way to bring it back, to maximize it. Obviously this is a big problem making this account almost useless. Simply put I can't minimize programs; if I do I lose them and the data they contain in the ether. So I have to do everything in the admin account and it is to avoid this that I created the regular account, for security reasons.
I am opened to any suggestion about this problem. The research I have done has been fruitless so far.
Thank you in advance.