Restarting the Foglight Management Server (FMS) solved the issue. A root cause cannot be found, but it could have been an overload situation.
To avoid an unexpected status change of the rules an automatic re-sync of the rules can be configured. The needed parameter can be initialized during startup:
UNIX:
./fms -d -Dfoglight.rules.full.sync.minutes=60
Windows:
fms -Dfoglight.rules.full.sync.minutes=60
Another option is to configure the parameter in the $FMS/config/server.config file. Make a backup copy of the file and add the following line:
server.cmdline.option0 = "-Dfoglight.rules.full.sync.minutes=60";
If parameter server.cmdline.option0 is already in use, use the next free parameter server.cmdline.option1 or server.cmdline.option02, ....
