You have the PF284 set to B Input and Mode 1 or X10 Address B1?
Mode 1. It is sending an X10 All Lights On to the House Code set on the House Code Dial and an On to the set address when triggered. An X10 Off when the trigger is removed. All other lights on the same House Code stay On.
Mode 3. X10 On and Off sent to the X10 address set on the PF284 House and Unit Code dials.
You would not happen to have an X10 plug in module you could connect on the same circuit as the PF284? That may help seeing if it is sending a signal and something has changed you power lines conditions. Like a new noise maker or signal sucker.
If you temporarily disconnect the alert console from the PF284. You may want to try a few different locations for the PF284 and see if the Test Button can control the switches from a different location.
Can you control the switches with another X10 controller. If not the switches may have the issue.
Jeffs Troubleshooting Tutorials.
https://jvde.us/x10-troubleshooting/Manual for the PSC01 that is the X10Pro version of a PF284