Late last year the State Department issued a ruling to give the works protection from seizure, lifting the Bronx Museum’s hopes that the show would happen. But by early this month, with no agreement from Cuba, Ms. Block said the museum decided it could no longer wait.

“We pushed as hard as we could,” she said, adding that curators from the National Museum were helping with the alternative show and that a loan of works from Cuba remained a distinct possibility in the future. Asked her feeling about the failure of the original show, which, with more than 100 works, would have been the largest collaboration between Cuban and United States museums in more than 50 years, she said, “I don’t want to call it disappointment because it’s been such a long process that we’re hopeful that it’s going to continue to foster cultural exchange.”

Ms. Block, who has traveled to Cuba for many years and long made the case that the island nation and the Bronx share important cultural and economic affinities, encountered resistance from some of the museum’s leadership in her push to make the show happen and to deepen ties with Cuba. Last year, seven trustees resigned and two publicly accused Ms. Block of a lack of transparency and of betraying the museum’s longtime focus on its borough. One of the departing trustees further accused Ms. Block of failing to inform the board that Cuba was unlikely to let artworks travel for the exchange.

In an interview last October, Ms. Block defended her plans and denied that claim. “The board was provided updates and information on the Cuba project on a regular basis,” she said, adding, “People outside the museum thought we’d never be able to successfully loan works to Cuba, and we did.”