These are the only options I've found that can temporarily correct it, no other Taskbar Settings seemed to make a difference:
- Toggling "Show taskbar on all displays" off and on
- Switching the selection under "Multiple Displays > Show taskbar buttons on" and switching it back
- Restarting Windows Explorer (or restarting the computer, which would also do this)
Each of these will bring icons back to all my displays, but then if a display is connected, it resets and hides my task icons again on secondary displays.
Can you also confirm another option that temporarily fixes it:
Have a window open of a program connected to the taskbar and while it's open unpin and re-pin it to the taskbar. For some reason that's another option that works for me.
Wanted to note that this also works for me, although its obviously not a fix. May assist in troubleshooting.
All of the icons that should be displayed appear instantly after I unpin one of the windows displayed on the affected monitor.