Has any pope ever visited Macau? I can't seem to find any information on it. If a pope hasn't visited Macau before, why not? The Catholic Diocese of Macau is directly administered by the Holy See so it would make sense to at least show once.
Has a pope ever visited Macau?
The short answer is no.
Macau is under Chinese administration. No pope has ever visted China or it's specially administrated regions such as Macau. The reason is quite simple: The Vatican has no diplomatic relation with the People's Republic of China. Even prior to 1999, when Macau was under Portuguese administration, Pope John Paul II never visited Macau. See Wikipedia's list of pastoral visits of Pope john Paul II outside of Italy.
There have been no official People's Republic of China – Holy See relations since 1951.
The Beijing government broke off diplomatic relations with the Holy See in 1951 after a complicated incident. Throughout 1950 and 1951, China had been putting pressure on the Vatican by threatening a breakaway of "independent Catholics", but many priests opposed the movement, and Zhou Enlai sought a middle ground. A deadly controversy was then manufactured: a priest working at the Holy See internunciature (legation) had thrown out an old 1930s-era mortar in a trash pile out of his home. A businessman named Antonio Riva discovered the mortar and took a non-functioning piece of it back to his house to display as an antique. When Communist officials saw Riva's curio in his home, they arrested him for conspiracy to assassinate Mao Zedong, which Riva denied. Riva was executed and the Holy See's diplomatic mission was banished from the country for "espionage". Tarcisio Martina, the regional apostolic prefect, was sentenced to life in prison and died in 1961, while four other "conspirators" were given shorter sentences.
The Beijing government has set two conditions for reestablishing the relations: that the Holy See "not interfere in religious matters in China" and that, in line with Beijing's One-China policy, it break the ties with the Taipei government that it established after the expulsion of Archbishop Riberi, ties that, since the United Nations' recognition of the Beijing government as the government of China, it now maintains only at the level of chargé d'affaires. - China–Holy See relations (Wikipedia)