Steps to reproduce:
- On a wiki (e.g. mediawiki.org) click on Preferences → Set your global preferences.
- Click on "Select options below to be global", the text, not the checkbox.
The checkbox gets checked, but the options below are still disabled.
The checkbox gets checked and the options below are enabled. Alternatively, nothing happens when the label is clicked.
This only happens under the "User profile" tab. For the rest, the text isn't clickable.
I've managed to reproduce this in both Firefox (65.0.1) and Chrome (72.0.3626.121).