I'm sure Epic made it clear 'you're next out the door if you don't get your #%%@ together and get a record out'.
That's exactly what I suspect. Maybe LA wasn't rushing her to actually give them a proper album but the second he was gone, I think things changed. This is how things work - the second you get even an average shift in personnel at a label (product manager, digital marketing manager, etc), things change. Mariah's mate basically just left the label and whoever is in coming isn't going to have the same affinity or offer the same passes.
What they are going to have is they've still got a new sign with no new music barring a pretty poorly performing greatest hits. It wouldn't shock me if it was "give us something or get out". And remember, Mariah doesn't have all that many options if (even as a legacy artist) she wants to remain in the lanes of major label funding and the advantages that brings.