I've read of other people on other forums complaining of slow green ups. One possibility that has been thrown out there is that the soil may have become compacted by excessive amounts of rain or water.
Moisture plus warm soil is essential.
The official soil temp is 56 F; and Growing Degree days (base 50) are 61.
This at a nearby Ag weather station.
Tiny and sparse yet, but there is a small amount of germination in the Midnight seeding--sown on top of snow on January 13, 2020. Whoops I meant to label this better. Still trying.
And I heard a familiar noise--it was a lawnmower! Homeowner started today! Also I saw some new mowed grass in the park acreage.
I'm in similar zone and overseeded + spot repair with midnight KBG last fall. It's definitely much slower than fescue as we'd expect. I also noticed some areas were as you describe: almost stagnated in growth & color. Most have grown & greened by now. The few that haven't are suffering from acidic soil and/or overcrowded seeding (I used a heavy hand in some of the most difficult areas).
Don't give up & don't sweat it unless you're seeing death symptoms. Just hold the line & be patient.