What are some examples of substantial voter disenfranchisement by electronic voting in the United States?

Question

I'm somewhat familiar with the Sequoia AVC case in New Jersey, from a Usenix paper by Appel et al.:

We found two design flaws of the AVC Advantage which may cause inaccuracy in counting votes [...] Thus, a voter may mistakenly think she has voted, when she has not; or a voter may vote, and then be invited to vote again by a pollworker who mistakenly thinks her vote was not recorded.
They are also consistent with a 1% undervote observed in the one precinct in which we subpoenaed “voting authority” stubs. In precinct 6 in Pennsauken, NJ on February 5, 2009, there were 283 Democratic voting-authority stubs but the public counters of the 3 AVC Advantage machines added up to only 280, with 280 votes recorded.

The Sequoia machine was used more widely than that, but it seems the paper refrained from estimating the total number of people disenfranchised.

What are some large cases (in absolute numbers of voters disenfranchised) in the US due to problems with electronic voting machines? Of course, numbers can never be entirely certain in such cases, so estimates are likely to be reported. To prevent this question from becoming a conspiracy theory magnet, such estimates would have to be published by reasonably authoritative sources.

Best/accepted answer goes to the largest number reported in an incident, as long I judge the analysis to be reasonably authoritative and evidence supported.

Answer 1

This example is probably the most notorious because the undervote was so large, in absolute terms but especially as measured by percentage of the vote and the margin percentage of victory:

In the 2006 Congressional race in Florida’s 13th District, candidate Vern Buchanan was reportedly ahead of candidate Christine Jennings by 369 votes. However, in Sarasota County, one of the five counties in the District, a staggering 18,000 votes were not recorded for the Congressional race. That was a higher under-vote rate (almost 13%) than in any of the other counties (in other counties, the highest under-vote rate was just under 6%, and the others were between 2% and 3%). ...in 2006 Sarasota County used paperless DREs. Therefore, there were no independent records of the votes cast in the polling places in that county. Some, including the U.S. Government Accountability Office, ultimately concluded that the under-vote was the result of a confusing touch screen ballot that caused voters to overlook the Congressional race. But because there was no evidence (paper ballots) that could be reviewed to confirm the intention of the voters, there was no way to dispute the electronic result. Following a lengthy legal battle Vern Buchanan was sworn in.