Despite Boston’s massive housing crunch and rents that are some of the nation’s highest, hundreds of new affordable housing units may be sitting empty as city officials work to find tenants. That’s according to City Councilor Annissa Essaibi-George, who said as many as 839 apartments for low- and middle-income residents may be vacant. On Wednesday, she called for a hearing on the issue. She and some developers said the sometimes monthslong vacancies result from a complex process for screening tenants and awarding the prized units — and from a city bureaucracy that is understaffed for the current building boom. Read entire article.