Hi Samantha,
Thanks for contacting us and sorry for the inconveniences,
This could be due to a number of reasons, such as:
- Your keyboard driver is outdated or corrupted and needs to be updated or reinstalled. You can check and update your keyboard driver by following the instructions in this https://support.microsoft.com/en-us/windows/mouse-and-keyboard-problems-in-windows-94b4ca7b-4f2f-077e-4eb4-f7b4ecdf4f61
- Your Ctrl + b shortcut is overridden or disabled by another program or add-in that you have installed or used recently. You can check and remove any conflicting program or add-in by following the instructions in https://learn.microsoft.com/en-us/office/dev/add-ins/testing/testing-and-troubleshooting
I hope this helps!
Regards, Sola