This loft at 50 Bridge Street in Dumbo has been on the market since the summer for $699,000. While the 980-square-foot pad is not as fancy as most apartments in Dumbo these days, it is priced relatively inexpensively and is in move-in condition. So what’s the hold-up? Could be that the low-ceiling mezzanine that rings the main living space is a tough sell. What do you think?