
Hi Daniel OBrien1
Welcome to Microsoft Community,
We are sorry for the inconvenience caused. Can you help us response these questions below?
Do you have other keyboards? Try using a different keyboard and test again if the Tab key works.
Do you have any plugins installed in your Excel application? Third-party plug-in interference can also lead to conflicts with some shortcut keys.
What is the version of your Excel application? Please click "Excel" - "About Excel" in the upper left corner to view.
Please share the above information with me, which will determine the direction of our next attempt.
Best Wishes
Ami | Microsoft Community Support Specialist