i have the same prob with emerald. support say emerald is a eventship and may not be sold.
but emerald is in the shiplist in harbour. free to purchase for credits.
at last night, some hours ago, i bought italian CL Abruzzi for 314,000 credits.
i think its another bug and again i contacted the support.
btw, abruzzi is a nice ship and a real killer in BK, lol.
now i'm waiting for EBB5/6 to buy them for credits. :o)