I have 23 liters (6 gallons) of a port style rose hip wine which is about 19 % ABV. Some months ago I measured the SG to 1.012. It was the same about a week ago. I sampled it, decided to back sweeten and added 230 g of sugar (10 g/l). I measured the SG today and it hasn't moved (I've seen no activity in the air lock either). Does it take that long for sugar to dissolve, or cold it be that the sugar, because of it's greater mass, stays at the bottom of the carboy?
As far as I know the sugar addition should've raised SG to about 1.016.
As far as I know the sugar addition should've raised SG to about 1.016.