Condominium owners across the country are facing a paralyzing problem: They can’t sell their properties because of a fast-growing and mostly secret mortgage blacklist.  Real-estate agent Paul Gangi was days away from closing a sale of his listing in Shadow Ridge, a 440-unit townhouse and condo complex in Ventura County, Calif., in December. That is when his phone rang.  “I got a panicked call from the lender saying, ‘Sorry, we’ve just found out Shadow Ridge has been blacklisted,’” he said. The buyer tried several other options for getting a loan, without success, and the sale collapsed.     Read the article…………………………….