Might it have something to do with oil extraction/fracking. There are oilfields around Prudhoe bay area along the north coast.
It is something that happens from time to time.
Sometimes the system fails to update a fairly wide geographic for a while. Usually it resolves itself but refreshing manually helps.
Aircraft often drop off the screen mid-ocean due to lack of ADS-B coverage.
Check Planefagging 101, you will find a map that shows the limits of ADS-B coverage.
It was only a suggestion, I'm a planefag not a geofag.
Just fired up my ADS-B & it looks like they are intentionally blocking NW conus area. It might still be just a system glitch though.
The Saudi medical aircraft has been popping into & out of US periodically for some time. Usually it take the northern route via Britain NE US but it does sometimes fly the southern Azores route.
No probs.
2-CRBU over UK looks like its heading for the midlands judging but altitude.
2-PGSI heading SW over Brest France probably en route to Spain.
Problems with ADS-B Mil over NW US no visible military aircraft good coverage with civil air though so it looks like intentional blackout of military flights.