Last year I didn't get my ballot until the day after the election, 4 weeks after it was supposedly sent (Lehigh County). Although the postmark was several weeks after the date the county claimed to have mailed it, so I suspect it was just sitting there for weeks. Unfortunately I would have had to travel 600 miles to vote, so I didn't vote. I don't think there is any recourse for this situation.

Edit: By the way, I think the ballot status page is not very meaningful. I completed and mailed my ballot back to Lehigh County two weeks ago, and they received it last week. But the "Ballot Mailed On" column is still blank.