For some reason, pressing "Add Text Box" shortkey doesn't let me add text box.

Because nothing shows up.
I use this “Text Box” a lot for pasting codes. So I decided to assign two shortkey for it.

But both of them doesn’t respond whatsoever. What to do? I really need this a lot.

Distro: Ubuntu 18.04, LibreOffice: 6.3.1.2