Back sweetened wine sugar not dissolving

[DragonTail]

Been back sweetening wine for a while now by directly adding sugar and using a paddle and drill to stir. Never any problems until now. Recently I added sugar to a concord wine, and a few days later I noticed it in the bottom of the carboy. Applied the paddle again and I see a fine while swirl in the wine. I am wondering why is this not dissolving when all the other ones I did worked fine? I assume the only way to fix this is just rack it off and leave the sugar behind?

In the future should I be making a concentrate sugar solution? That provides it's own challenge because it is adding liquid. Is powdered sugar a viable solution?

 

[winemaker81]

Are you using granulated table sugar?

How much did you backsweeten? I ask this as if you're adding a LOT of sugar, it's possible to exceed the wine's capacity to absorb it. I suspect this is not it, but it provides a data point.

Are you positive the sediment is sugar and not lees?

When backsweetening, I pour the sugar in a thin stream while stirring, and have never had a problem with the sugar dissolving. However, I tend to backsweeten lightly in comparison to other folks.