The outage that began over the weekend continues into Monday afternoon, ARRL confirmed by telephone to K0MB. There is no notice of the outage on the LoTW or ARRL web locations.
It was working earlier today for me when I did a manual upload to LoTW. But tonight, they are doing some work on it as described here. http://www.arrl.org/news/arrl-headquarters-systems-down-for-maintenance-wednesday-evening 73, -Rob