And even here [
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], you can see Orochimaru referring to them being able to "feel his chakra despite not being sensors" meaning sensors merely feel chakra better than the average Shinobi. They do not sense every trace of chakra or see every trace of chakra, they merely
feel its presence. How can they "feel" it when it's being suppressed? Does that give reason to assume that if it's not able to be felt, it's not capable of being seen? Nope.
Sharingan sees the faintest traces of chakra [
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][
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], Mu is not hiding from the Sharingan. There's no debate here, at all. It will be seen as it is there. Sharingan sees faint traces of chakra through objects and skin/muscle. Mu's body will be entirely explored, meaning the chakra will be perceived, meaning Mu's location is discovered.