I had a Blackberry Wine from Vintners Harvest Fruit Base that smelled off for awhile.....It tasted okay and we eventually bottled it.
We used RC-212 yeast and thought that was the cause, it it know to cause gas.....
At first we would decant it, which would clear the odor and then the smell went away on it's own.
I think the big guys would tell you to stir the Devil out of it....
Have also heard that if you sweeten it a bit that might go away....Personally we don't care for sweetened wines.