Of course, it takes two to tango and there’s also the fact that neither Harmon or Roiland seemed willing to sign off on whatever deal was proposed.
That’s assuming that’s what the issue is anyway; it’s entirely possible the contract contained other things that Roiland and Harmon didn’t agree to.
But since they’ve crafted a massively popular show, who can blame them for wanting to get paid?
Both Harmon and Roiland assured fans the hold up on Rick and Morty had nothing to do with their want to make more episodes, but that Turner was the one holding things up.