Locate object vs objects in the ethereal plane

[Joran0100]

OK so I have a question, if you use locate object to locate something on say a succubusses body like armour or a weapon, and then she goes to the ethereal plane can you still track her movement because she is still within the distance limit of the spell but I don't know if there's any rules about locating objects on the ethereal border which is where she goes if I'm not mistaken

[CheddarChampion]

I think it should work if you cast it before the object was moved to the ethereal plane.
Maybe even if you cast it afterwards...

The idea is that the ethereal and material planes take up the same planar space but don't interfere.
In which case an object can be close when measured by feet/meters but out of reach.
It seems like the locate object spell only cares about feet/meters, so I'd say your example would work out well.

Just keep in mind you know the direction but not the distance. Trying to predict where the succubus reappears could be tricky.

[Chronos]

Distance is only meaningful on the same plane. For a spell to work across planes, it has to explicitly say so.