After the very extended set of bug fixing updates on PC, they eventually had to call it a day after getting things to a reasonable state there. The decision was made over whether it was worth spending the time porting it over to console knowing that first they'd have to create a current gen console version since PS4 and XBone versions were a no go.
Then they just decided to write off the whole expansion financially anyway, work with what they had and carry on just with the reduced workload of a mostly working PC version.
Not their first choice, but given the mess that Odyssey was on release (i.e. struggling to run well on the very top line PCs) this is about as good as could have been hoped for.