I think I found the solution. At least this fixed my Brothers MFC-L8850CDW.
I uninstalled all of the brothers' software and rebooted as prompted. I installed a fresh install of the "full driver and software pack." (This step is likely unnecessary; it's just information about what I did.)
Open Brother utilities, go to the tools tab and run the installation diagnostics. Confirm the state of the scanner. (Mine said it failed, and all others passed.)
Navigate to the control panel for Windows by searching for "control panels" in the upper right search bar and typing "scanner." From the results, click on "View scanners and cameras." Confirm that the scanner and cameras are empty.
Go to the brothers' site and download the driver-only pack. Extract the pack and open the extracted file folder. From here, you are looking for "applications" I had two; mine were "dpinstx64" and "dpinstx86". I ran both for overkill. (double-click the file name). (You shouldn't see anything happen)
From here, go back to your scanner window in the control panels and click "refresh." You should see a scanner populate. Test and start scanning.