Excel shortcut freezes spreadsheet until I click on it with mouse (Excel 2019, Windows 10 Pro)

Problem:

I switched from Office 2016 to 2019 via Office 365 subscription. Since then, my spreadsheet does not accept any keyboard inputs after I use the shortcut in Excel to change either font color (alt-h-fc) or fill color (alt-h-h). The only way for me to reset it is to click on the spreadsheet with my mouse. 

I did the same upgrade on my laptop (that one is Windows 10 Home though, not Pro), and I do not have the issue there.  

Pictures:

1. As I am performing the shortcut to select a font color

2. After I press enter to select a font color, I am now unable to move with keyboard. Even when I press escape, random letters, etc., nothing happens.

If I click the spreadsheet with my mouse, everything goes back to normal. Also, notice how the "m" from the shortcut font color menu is still present for some reason.

*This also happens when I use the shortcut for the fill color

What I've Tried Already:

1. Repair option

2. Online repair option

3. Uninstalling and reinstalling Office 365

Please help! Thank you in advance.