Getting taskbar with clock (notification area) on second monitor with Windows 10

My Windows 10 updated itself this moing and now the notification area (the rightmost part of the taskbar with clock) will only appear on the laptop monitor. The past several weeks it was happily appearing on an exteal monitor.

I'm on a Surface 4 with two exteal monitors (both DisplayPorts). Monitor 2 is my main monitor and I've extended the display to the other two. All monitors show taskbars, but the notification area only appears on the Surface. Any ideas?