Simply put, we do not know if the Dwarf rings conferred invisibility and therefore it cannot be assumed that they did. Sauron would have no reason for imbuing such a power on the Dwarf rings, much as he would have no reason for doing so for the Elven rings. Sauron knew that Elves and Dwarves would not be turned over to the wraith world, and the only purpose of invisibility in the One Ring and the Nine Rings was to make the wearer visible to those in the wraith world (i.e. when Frodo puts on the ring and the Witch-King is instantly aware of him).
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...where the instrument of intelligence is added to brute power and evil will, mankind is powerless in its own defence.
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