So it's not about sanctions. It's about pricing.
The Indians were buying at a $30/barrel discount to Brent Sea Crude.
If they are not being offered it at this discounted rate, they probably do not want to buy it.
The price of a FUNGIBLE COMMODITY is a function of the freight to get it from the seller to the buyer in relation to other suppliers of the same product.
Also, there are refineries that are more adept at breaking down high sulfur crude and others that can only breakdown sweet crude.
If there is more demand in the market for diesel or heating oil in the winter there may be more demand for high sulfur crude that comes from places like Venezuela.