Was having same issue, kept getting errors when I tried to bring up motion detection screen under advanced settings. FINALLY figured out how to get it back, it's a multi stage process.
First you must allow these add ons
Java Deployment Toolkit
Java Platform SE 7 U
then you must add these security exceptions to the Java app under security
I found that I had to all ALL THREE for EACH of my cameras:
http://192.xxx.0.xxx
https://192.xxx.0.xxx/motion.htm
https://192.xxx.0.xxx/setSystemMotion
NOTE that the first url is http while the others are https,
of course the xxx's are for your camera's url
and LASTLY, at least in Firefox, you have to give permission each time you bring up the advanced settings window, clicking on the upper left corner of the address bar and allowing the app to run
it took me HOURS of fiddling but I was able to bring up the motion detection set up screen on each of my 3 cameras