Back in grad school a colleague of mine spent nine months on an experiment in a new field and submitted it as a paper to a quality journal. Six months later, the paper was rejected for lack of novelty: One of the reviewers had found a paper with a figure-by-figure duplication of the same experiment -- published on arXiv a week before the rejection decision. Both the managing editor and the author on the arXiv paper were from Chinese universities.
We wrote a rebuttal and submitted a complaint to the journal editor, but no justice was forthcoming. My colleage switched research directions to avoid the collusion and now takes pains not to submit papers without a coauthor who has enough clout in the field to deter blatant research theft. He also avoids dealing with editors from institutions in China.
He ended up graduating two years later than planned.