Text Preview App – Settings/Opentype features Button doesn't work

nothing happens when I click on the button

Text Preview 1.0(8)
macOS Catalina 10.15.3

As a workaround, you can use @hagenburger’s Export and Install script:

It is also described at the end of the Eliminating Font Cache Problems tutorial:
https://glyphsapp.com/tutorials/eliminating-font-cache-problems

That seems to be an Catalina problem. I’ll have a look.