STEPS TO REPRODUCE:
- Go to Notifications > Settings
- Observe the Filters section
- Add some more filters (to add Page 2)
All filter toggles are displayed properly.
The toggle of the last filter from the bottom of each page is displayed as a checkbox. The issue reproduces on all tested browsers: IE11, Edge, Chrome 68 and Firefox 61 (including incognito mode).
I could not reproduce the issue on XWiki 10.6.1.