Windows 10 October 2018 update screwed up mouse highlighting.

As 1809 is the newest release of Windows, expect some bugs in it until Microsoft starts servicing them.
Please file a feedback in Feedback Hub(Win+F) and roll back to 1803 until this is resolved.

Please try these options one by one and check after each option.

1 - Use the Hardware & Devices Troubleshooter
Type Troubleshoot in Windows Start Search Box > Click Troubleshoot > Click Hardware and Devices > Click Run the troubleshooter and follow onscreen directions

2 - Take actions related to mouse
Windows Key+X (Or right click on Start) > Click Device Manager > Expand Mice and Other Pointing Devices > Right click on the mouse listed there >

A. Roll back - Click Properties > Roll Back - Under Drive tab, if Rollback Driver is enabled click it > Reboot

B. Uninstall - Uninstall > Reboot and the driver will be automatically installed

C. Update - Update Driver > Click Update Driver Software > Click Browse my computer for driver software > Click Let my pick from a list of device drivers on my computer > Choose the driver > Click Next to update > Reboot
If this does not work, select Search automatically for the updated driver in place of Browse my computer for driver software > Reboot

Source - https://support.microsoft.com/en-us/help/17417/...

I can remember when our IT guy had one solution to every issue "turn it off and back on".

Seems that's the new Microsoft mantra.

One would think they would thoroughly test before putting it out.

Only one sound conclusion can be reached - I should have bought a Mac.

I can confirm that this is also a problem in Windows 10 1803.  Going to Computer Management and uninstalling all mice (including trackpad if you have it) and using the keyboard shortcuts to restart may help somewhat, or may not.  This forces the mouse driver(s) to be redetected on startup. In my case, it didn't help, but others have seemed to have some positive effect by doing this. 

Thanks for the advice. But I have no idea how to "rollback" an update.

Thank you I will try those suggestions