The selection a special character that has been marked as a favorite toggles the favorite button into 'Remove from favorite'. When I click 'Add to favorites' the current selection goes to the list but the button remains in its add state. It should immediately change.
Akshay Deep committed a patch related to this issue.
It has been pushed to "master":
tdf#109217 - State of the favorite button is not updated immediately
It will be available in 6.0.0.
The patch should be included in the daily builds available at
http://dev-builds.libreoffice.org/daily/ in the next 24-48 hours. More
information about daily builds can be found at:
Affected users are encouraged to test the fix and report feedback.