getinfo in the wallet shows difficulty: 0.52631790, whereas the spinning block loading tooltip shows difficulty at 0.0000 something.
Is it possible that staking is stuck because it is using the higher difficulty that getinfo shows.  I noticed the same thing when the 0.7.6 wallet was released and we were stuck on block 5600 for hours.
Staking at a difficulty of 0.5 would take a long time and that is what we are seeing at the moment with block 6419.
Its POW you should watch that POS!
{
"proof-of-work" : 0.52631790,
"proof-of-stake" : 0.00001526,
"search-interval" : 1
}