Jeremy Boga - The likely scenario:

I believe Chelsea are trying to work out a condition that will allow them to be in control of Boga at Sassuolo.

They don't want Sassuolo to sell him, which will mean losing control of the player. Rather they want Sassuolo to keep him.

For Sassuolo to agree to that, there must be a renegotiation. Sassuolo won't accept to keep him for Chelsea without any gain. They rather sell him now. So, Chelsea will have to increase the buy-back fee for Sassuolo to agree. And it's a win-win situation.

Sassuolo get to keep the player for another season, Chelsea still in control and will pay a higher fee to Sassuolo or forfeit (lost nothing).

Why I believe this scenario is this: If Chelsea want to sell off Boga, they will rather buy him back and sell him for a bigger fee.

That's the only negotiation I see on the table. It's better than accepting a few millions from Sassuolo to cancel the buy-back clause. I really do see that BUT nothing is impossible in football.