The museum is in the midst of its fourth application to have the collection accepted by the panel, the Canadian Cultural Property Export Review Board, which certifies donated works as nationally significant and then determines their value.

The panel has granted such status to only 762 of the prints, at a value of $1.6 million.

In the meantime, the entire collection is in storage and Ms. Leibovitz has received only half of the promised $4.75 million. By contract, she does not receive the rest of the money unless the government panel signs off, according to Mr. Mintz.

Just how this ambitious, but now stalled, art initiative was born remains unclear. Ms. Leibovitz, through her gallery, declined to comment. The museum said through a spokesman that it did not come up with the idea. And Mr. Mintz said only that he was approached by “knowledgeable art-world figures” after the idea for such a gift arose.

He declined to say whom, citing a confidentiality agreement.

Mr. Mintz was the second businessman to consider buying the collection for the museum. The first, Larry Rossy — founder of the Canadian discount chain Dollarama — dropped out in 2012 after beginning the application process for a tax shelter, according to the CBC. He declined to comment on why he withdrew.

Mr. Mintz, who said he was approached about the gift a few weeks later, said the opportunity attracted him because his mother had been a big fan of Ms. Leibovitz.

At the time of the gift, he said Ms. Leibovitz preferred that this collection — with prints of her Rolling Stone cover of Yoko Ono and John Lennon and images of the Blues Brothers — go to a smaller museum. “She felt it would have a greater impact than in a large, established institution,” Mr. Mintz told The Toronto Star in 2013.