I've had similar problems on an rather large OKK CNC with a Bosch Controller.
Part of a cycle to say change a tool operates various mechanisms in sequence.
Cycle starts first part of sequence. Waits for a limit switch to say that part of cycle is complete.
Next step commanded, wait for next limit switch.
Each sequence starts moving something.
That sequence is usually completed by hitting some limit.
Eg Tool picker at location ready to pickup a tool.
If any of the limit switches are not sensed correctly, or at all then the cycle waits, hence the green light just waiting.
Also some parts of sequences may be progressed based on timers instead of limit switches. If a time is set to short, or something does not move fast enough to get to it's next spot, because it's gummed up that can do it too.
Easiest thing with limit switches is putting a 0.1uF Capacitor across the switch, so you get the capacitor supplies extra wetting current to keep the contacts clean. This is usually a safe fix, if no capacitor is across a switch.
If it causes some operational grief, then just remove it.
When the machine is 'stuck' try thumping around the areas where the limit switch(es) are/is and you may identify it. Careful of unexpected movement if the machine normally moves FAST.
Every case I have had on an aging machine has been tardy limit switches.
Clean plunger mechanisms and get rid of gummy old lubricant.
May appear temperature related, because lubricants get more sluggish at low temperatures.
Also look at connector plugs. Make sure all pins have positive pressure.
Search and destroy....... It will fix it. Don't blame software. It is just doing it's job. If it worked yesterday, it ain't broke.
