@arnold_r_clark said in Weird behaviour homing Y-axis (only):
When you home with a Z probe the X and Y homing code has commands to raise/lower Z to be sure the nozzle is clear of the bed.
im sorry but that statement is not 100% correct which you tried to cover by stating "but varies with the specific end-stop sensor and z probe type" so in effect your initial statement should be preceded with "in my opinion"
That part about moving Z up/down during homing X and Y does not depend on the type of hardware. It's about being sure nothing is touching the bed during the XY moves.
And the statement about "varying" was part of the sentence dealing with speed and it is not an opinion.
And to throw another spanner into the mix what about a z probe that uses an optical end-stop on its trigger ?
The only device I know like that is servo based and you have to deploy/retract some part of it, which takes time. A Z endstop if fixed in place.
Frederick