Routing over closed North Cascades Highway

ABRP is routing me over the North Cascades Highway, State Highway 20 in Washington state (USA), even though it is closed for the winter. Routing from eg Winthrop, WA to Bellingham, WA (or any city pair in a pretty wide region on the two sides of the highway down to the northern Seattle suburbs) will show this issue.

(I see past tickets about ABRP not routing over the North Cascades Highway in the summer when it was open; this is the opposite issue. The highway closes from roughly November through April/May each year.)

I indicate this as happening on iOS, but it also happens on the web and presumably any other platform.

https://abetterrouteplanner.com/?plan_uuid=789be0bb-405b-42e9-b61f-2184e58d2e2a