(pretty old problem - since at least 12.9) When working on multiple screens with taskbar showing only apps on the affected screen then icon on the taskbar does not show on the same screen as the TOAD application window.
I have a laptop's 1600x900 and an extra 1440x2560 monitor (pivoted). When I drag TOAD window to the extra screen the taskbar icon does not follow and stays on the laptop's screen taskbar.
If I drag any other application the taskbar icon follows the application window between monitors.
Thanks, it's a known issue. An unfortunate side effect to the solution to other problems. It's on our radar to fix both.