Image result for atom ide logo
It is invisible because the font color and the background color is the same. This happens because of the new Yaru theme. So what you need to do is to change the theme. So lets see how we can change the theme.



Step 1: Go the ' Ubuntu Software ' and Search for 'GNOME Tweaks' .



Step 2: Install the application and Launch the application. 

Step 3:  From the Side bar select ' Appearance '.



Step 4: Under 'Themes' option select 'Applications'. And change it to your desired theme. I recommend using 'Yaru-dark'.



Thats it.
Your problem is solved. Comment down below if you have any doubts.