The first thing coming to mind after complete absence was conspicuous absence, and Google ngrams seems to support my instinct that it is more common than other solutions (besides "complete"):
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Though "complete" is more common, it seems to me that it is also more neutral.
If I wanted to emphasize the obviousness or strikingness of an absence, I would use "conspicuous.""Marked" and "noticeable" could be considered of the same flavor.
If I wanted to emphasize the completeness of an absence, I would pick "complete" or "total," or even "utter."
