I believe they want to keep their options open, with an eye towards moving on from X after this season.So you believe Miami wants to see him produce in 2021, then adjust his contract for the balance of the terms and keep Howard in Miami?
That is likely why Grier/Flo have no interest in completely redoing the contract to include high future gaurantees.
I would assume they have offered whatever is their version of a "compromise", and X's camp has rejected that offer.
If that is indeed the case, there really isn't much to negotiate.