[2.0.x] G28 Command Is Broken, Doesn´t Take Y In Combination With X ...

Today I had a very large and time critical 40 hour print job fail 20 hours in because of a bad bowden coupler at 4 AM. So I pause the printer (advanced pause yay) and proceed to fix the extruder. Then I realize that since a minute passed before I spotted it, half a layer is missing, so I can't just resume the print...

Ok, no problem, I'll see where it stopped extruding and start the Gcode from there, I've done it several times. For this I will connect the computer to the printer which will cause a reboot and position will be lost. This is ok because as long as I don't touch anything, the printer shouldn't move more than 8 microsteps when the steppers power up again, specially the Z since that can't be homed with a full print bed.

I then cut the gcode to where it left and make the neccesary modifications for it to work standalone, such as G92 to actual Z position, correct feedrate for the move, etc. One of this modifications is to home X and Y (in hindsight, probably should have left it alone...) but not Z, since it would crash with the print. So I try to do a G28 X Y to home just the X and Y axis and this is where the bug showed:

G28 X Y only homed the X axis. It completely ignored the Y.

So this messed with my positioning, which led to a very frustrating time getting everything ready again and trying to resume the print. G28 Y works fine, but in combination with any other axis, the Y is ignored. G28 X Y Z will only home X and Z and G28 X Y will only home X. Ended up using G28 X followed by G28 Y.

On another note, isn't there any way to avoid the printer from raising Z when homing? This also caused me some grief and I could't find any way to disable it, the only relevant line is //#define Z_HOMING_HEIGHT 4, but thats commented out and is 4, when in reality the Z rises 5 mm. Googling I found that this setting was exposed before with Z_RAISE_WHEN HOMING or something like that, but it's no longer present.

Sorry for the long rant, I only slept 1 hour today becuase of this :) Merry christmas.

That printer is using Marlin 2.0.x from September, but issue is also present on my other printer with 2.0.x from December 8th, so I would expect it to be also present on the latest one, since I found no related commits since then. Sorry for not testing it on the latest, but gotta sleep some...

Attached are the config files. G28 X Y bug.zip

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