@Chris Clancy1:
After going through a process with Brother support walking me through their idea of recovery and still not being able to print, they told me to try another machine. I declined and discontinued that phone call. What I describe below is my own success path from memory, but I think I have it described accurately.
I found that I had to go through a particular process to make the USB attached printer work again. I may have done more than is absolutely required, but my Brother HL-L3219CW printer works now just as before the Microsoft Security Update.
1. In windows (in my case, 64-bit Windows 10), I went to Control Panel and
a, Clicked on "Hardware and Sound".
b. Clicked on "Devices and Printers".
c. Right-Clicked on the icon representing my Brother HL-L3219CW printer,
d. Clicked on "Remove Device".
2. Disconnected the USB cable from both my PC and the printer.
3. Went to the Brother USA website at: Brother Business Solutions: Enterprise-Grade Printers, Office Electronics & More (brother-usa.com)
4. Clicked on: the dropdown arrow next to "Support"
5. Clicked on "Software & Driver Downloads".
6. Entered my printer model: HL-L3210CW
7. On the resulting "Downloads" screen, I selected Windows 10 (64-bit), and clicked the "OK" button
8. On the next "Downloads" screen, I selected "Full Driver & Software Package (Recommended)". I noted this was released in 2020.
9. I then powered off the Brother HL-L3219CW printer by holding down the power button located just below the small display screen on the top left surface of the printer when facing the printer. Hold down the power button until the display shows "Shutting Down". I left the printer off.
10. Restarted my PC.
11. Powered the printer back up.
12. Connected the USB cable to my PC and the Brother printer.
13. With the USB cable still unconnected from both the printer and the PC, I clicked on the icon of the zipped Software Package.
14. Observed that my printer was now showing in "Devices and Printers".
15. Printed a test page successfully.
I hope this works for your clients.
Regards,
Tony