If you're clicking and dragging with your mouse and seemingly unable to select text, please check to see if the following are true:
- You're using your Mac in "Dark" mode (under System Preferences > General); and
- Your selection color, under the same control panel, is set to "Graphite" or something similarly non-contrasting.
If that's the case, then likely what's happening is that you are able to select text — just you're unable to see that it's selected.
To fix that, please try one of the following:
- Change your Fade In custom page/text colors to light-on-dark under Preferences > User Interface > Page Colors
- Uncheck Preferences > User Interface > Use system selection color to use Fade In's built-in color instead (which shouldn't have the same problem)