I finally got around to reading the forensic Chronicle account of turmoil at the anthropology journal HUA. The story, by Jesse Singal, is worth a read—it is an impressively thorough and fair-minded act of journalism. Perhaps unsurprisingly, the APC shows up in one of the piece's many subplots:
Starting in the spring of 2015, HAU began asking authors for so-called article-processing charges, or APCs, to help support its open-access model in lieu of subscription fees. The way it usually worked was this: University departments or libraries often have some funds set aside for these sorts of expenses, so when an author’s piece was accepted, the author would sign an agreement stating that he or she would attempt to obtain funding, if possible. But it was generally understood that this would not be a prerequisite to publication — HAU was open access, after all, and its financial ethos centered on making academic publishing more accessible to all, readers and writers alike.
Singal describes how an author the journal had published was threatened with retraction for not—or so the editor judged—making the required "good faith" effort to track down APC dollars:
“At this stage, after 7 months of waiting, the burden is on you and your institution,” [the editor] wrote. “Should your institution be unable to cover the APC, the best I can do is to offer a 50% discount.”
“I was obviously really surprised — I kind of scrambled to do it,” recalled [the anthropologist author]. Having a paper disappeared from a publication “would be really bad,” since under normal circumstances that signals fraud, plagiarism, or some sort of major error. [The author] was able to successfully apply for 2017 APC funding from Tufts, resolving the situation. She said she had never heard of an article’s being pulled from a journal for nonpayment of a fee.