Why does my cursor completely disappear from my screen when it is docked?

[the whole taco]

cursor disappears

My cursor disappeared completely from the screen(s) when docked.
I have just spent a few hours trying to suss this out to no avail.
I thought I had seen a thread on this issue before but couldn't find it with the search.

On occasion in the past it used to disappear but after waving the mouse around it would appear soon enough.
I have an external monitor and wired mouse and keyboard via the dock.

I tried reboot. undocks. replug usb ports. change mouse cursor look and feel.
nothing worked.
You can see where the cursor should be displayed as certain parts of the screen are highlighted or bubble text appears, so it is tracking ok. It is just there is no cursor displayed.

I eventually got it back from undocking, detaching type cover, reattaching type cover and redocking.

anyone know the cause of this?

The occasional problem used to occur with type cover attached.
Recently I have been docking without type cover and just using full size keyboard which is when it disappears for good.

 

[the whole taco]

update:
problem seems to occur after using as tablet then redocking without keyboard (seems to think it is still tablet?)
I have changed over from a wired mouse to wireless. same issue

workaround:
the easiest way I have found to resolve this is:

• Charms bar > Devices > Project
• select PC screen only
• select extend display

cursor reappears across all displays.