Some recent versions of fr24feed set the ownership of dump1090-mutability to 'nobody:nogroup'. This causes 1090dump-mutability maps and graphs to stop working. sudo chown -R dump1090:nogroup /run/dump1090-mutability to fix. Maybe suggest turning off FR24 auto updates if you are feeding them until issue is fixed.
pre and post installation scripts really poorly coded...they've made such a mess. as for the purpose to increase traffic on forum, sure they got a target!