Here is my opinion of why I think Jerry has a problem signing Dak:
Romo had problems and everyone said he needed to sign OL. So Jerry went out and got Great OL, three or four paid at the top of their positions.
They needed a RB, so he got the best out there, and with that OL he was the best -- and demanded to be paid like it.
They had a receiving issue, so he went and got an awesome route running WR -- who wanted paid.
All these high priced players, should make an avg QB look good. Top WR, Top RB, Top OL.
Jerry thought the name of the Cowboys and the fact that he put all these top players there would make the QB want to take a little less, and stay; especially since these guys had made him look good.
Only Dak hired an agent that said: "No I want my guy to be the highest paid -- look at how good my guy is -- after Jerry paid the OL, WR, RB".
Jerry doesn't mind paying, but paying for a 4-12 and 8-8 seasons wasn't what he was bargaining for.
Will Dak get paid -- Yes. Will Dak get paid what his agent wants by the Dallas Cowboys -- Not likely.
IMO, if Dak hasn't signed long term before the draft, then Dak won't be in Dallas past one more year. They will make new plans without Dak in them for the following year, and Tag him this year. They not just won't tag him the next year, they won't try to negotiate with him either.
15% of a $180M is $27M. One of 52 players making 15% of your cap gets problematic. Dak's agent seems to want much more than that. This is still a team game, regardless of what agents seem to think.