Ok I've got a good one for you! Mach 3 version R3.043.066. Today, after firing up the machine, I ran an ref all home. Put a new bit in the holder, put that in the head and jogged to z zero.
Adjusted the tool offset in settings then ran auto set tool length offset, and shut the program down. Restarted mach, and ref all home. When referencing, Z and X referenced, as did the first Y sensor, but the second y sensor (which is labeled as A in config, just kept on going like Forest Gump. The sensors are all illuminated, and while the Ya sensor passed over the bolt, the light turned off, even though the gantry kept on going. I took screen shots, and made a video. While y was traveling towards the sensor, the following text displayed. "requested home axis home switch is active..please fix them home"
I am a total noob at this. Been operating this machine for 3 years now, and each problem is a whole new world to me. This one seems to have popped up our of no where, and doesn't seem to be caused by things I did. Here is a video of me looking through some things... https://youtu.be/-pztbDToHvc