Right you are...unless it is not sitting level, I suppose. Most common way to lose fluid is through a small hole in the cooler line at the bracket where they are supported at the block-bellhousing joint. Second most common, perhaps, is a worn tail shaft bushing and seal. Look around those two places for evidence of the leak.

Some of us old timers may recall when the engine load information was delivered to the automatic transmission via a vacuum operated bellows device called a "vacuum modulator" which, when leaky, caused the motor to suck up the ATF and burn it. Fluid disappeared without an apparent fluid leak. This is not the case with your Volvo.
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Art Benstein near Baltimore

We childproofed our homes, but they are still getting in.