Are their blinds or curtains on this door?

If so, open them immediately and leave them open.

Corners will be possible air leakage pathways. Can be just a weak point in the weatherstripping arrangment or you can have a small kink in the weatherstripping that is allowing for cold air to enter into the inside space.

What’s your % humidity?

Ballpark of 27% humidity

Is 27% programmed on the humidifier, or is it a hygrometer reading? If the former it may not be accurate, and even if it is, it may still be too high if you are dealing with sub zero temps overnight, OR something impeding circulation like the curtains mentioned above.

While there could certainly be some wear or defect of the weatherstripping in that area, its more likley that its just a combination of the limitations of that door to seal, the interior RH, and the extrerior temp.

Even the best windows and doors do not seal 100%, and while its a well built product, the Marvin door line isn't on the top of the "air tightness" list.

Big +1 to above. There can be big swings between what is on the humidifier setting and what is being seen in the home. Needs to be check with handheld hygrometer and in the area in question.