“Some issues were raised,” Mr. Stein said in a telephone interview. “We are, as a board, working on those issues — that process is underway.

“I’m not prepared to say whether they’re valid concerns or not valid concerns,” he added, “but the board will take them seriously. To just say we’ve got these concerns and goodbye — that’s not the way to do corporate governance.”

But Ms. Blanco said she and others had raised these issues before, and that they had not been addressed. Ms. Blanco — a former entertainment executive who was born in Cuba and raised in Miami — said the first troubling development was Ms. Block’s decision last year to help host a party in the Bronx, held by local developers to promote an expensive condo project. The event was later criticized for exploiting the South Bronx’s troubled history and representing excess in one of the country’s poorest neighborhoods.

In an interview, Ms. Mandanas said it was corporate governing issues that most concerned her, namely that museum executives were not running their proposals through a recently adopted strategic plan, and that the institution appeared to be facing a deficit of an uncertain amount. “It was represented as various numbers — one was several hundred thousand, one was $100,000 — we couldn’t get a sense,” she said. “It was a real red flag.”

In particular, some board members took issue with Wild Noise, the museum’s initiative, announced last year, to exchange works of art with the National Museum of Fine Arts in Cuba. Only in the middle of fund-raising, Ms. Blanco said, did she learn that Cuba was unlikely ever to release any artwork, for fear that it might be seized to satisfy outstanding claims from Americans whose property had been confiscated by the Cuban government.