Fattah’s lawyer Khaled Ali, a former presidential candidate, said he received another permit to visit, but was blocked again.
"I picked up the permit from the public prosecutor's office in Cairo at 3:00 pm (1300 GMT), and I went as quickly as possible" to the prison, he said on Facebook.
Ali added he arrived at the Wadi al-Natroun prison, about 100 kilometers (60 miles) northwest of Cairo, around 4:45 pm, and was allowed inside and made to wait. But an hour later, an officer informed him that "the prison was closed," Ali said.
Ali had previously been denied access on Thursday, after prison authorities said his permit was invalid because it was dated the day before. Such passes generally have validity for "one week," he said.
Abdel Fattah began refusing water on November 6, seven months into a hunger strike, as world leaders arrived in the Egyptian resort of Sharm el-Sheikh for the COP27 climate summit.
A key figure in the 2011 uprising that toppled longtime dictator Hosni Mubarak, Fattah is serving a five-year prison sentence for "spreading false news" by sharing a Facebook post about police brutality.
On Saturday, his sister Sanaa Seif and hundreds of activists held the largest protest since the UN climate summit began.
Although demonstrations at COP27 must be approved by organizing authorities and should take place only in a special zone, activists behind Saturday's rally said they got UN permission for their action outside the designated area.
On Friday, his other sister, Mona Seif, submitted a pardon request.
The plea was picked up by one of Egypt's most watched talk show hosts, the ardently pro-Sisi Amr Adib.
On prime-time television Friday, Adib said the pardon would be in "the interest of Egypt first and foremost."