GMAT Sentence Correction (SC) | Reporting that one of its many problems had been the recent

Saw the below clear response by ManhattanGMAT Staff. Thought I should repost it. Because the answers here weren't very clear for me on why it should be "had" and not "has". See original thread here: https://www.manhattanprep.com/gmat/foru ... -t763.html

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