Switching between user or from editor to schema browser application gets hide

I have latest Toad Expert for Oracle version 12.1.0.22. Whenever I switch between the user or at times switch between editor or Schema Browser, Toad application hides immediately behind the application. I used to have version 11.5 earlier after I upgrade to 12.1.0.22 since then I have this problem.

Any solution for this behavior.

Thanks,