I was pulling my hair out as I couldn't add 3D text to my sparkar filter... the option was simply greyed out and therefore I couldn't even select it.
The solution is very simple indeed - simply go to
PROJECT
EDIT PROPERTIES
and deselect the INSTAGRAM option
Then you can add any 3D text you like.
NOTE: I also briefly show you how to adjust the text language, format, position and color / material / texture.