Weird intermittent bug involving proximity sensors and homing

Here is my control box and the CNC it controls ... both my own design and fabrication

Can't say ... how can I verify ? (about the 5i25 flash ...)

Can you measure the 7i77 input 07 with a voltmeter relative to field power common
in both switch states and both drive enable states?

That is measure from TB8 pin 8 to TB2 (orange) pin 8 in all states

If you had a noise issue with serial communications I would expect to see
error pop-ups in axis

That looks like an imminent fire hazard !
As Todd mentioned, that is a noise issue form motor drives, and after looking at the pictures that is the first think to look into. Grounding problems can occur in many ways, but from experience the first thing to look at is : did you change the power outlet ?

What is weird is that I didn't change anything ...

PCW wrote: Can you measure the 7i77 input 07 with a voltmeter relative to field power common
in both switch states and both drive enable states?

That is measure from TB8 pin 8 to TB2 (orange) pin 8 in all states

If you had a noise issue with serial communications I would expect to see
error pop-ups in axis

Here are the voltage values ... now the relays are not changing values ... getting worse

Drives disabled, port 7 opened = 24,2V
Drives disabled, port 7 closed = 0V

Drives enabled, port 7 opened = 24,2V
Drives enabled, port 7 closed = 24,2V ... the relay is now not working on all of them ...

How do I find a ground loop ?