I also have been having trouble ordering diapers. Well, no problems ORDERING, it's the delivery that's been delayed. (Not Northshore, two other companies that I order from..) There is a delivery/shipping/trucking problem all over the U.S. and in many other countries too.
In my case, I didn't need the diapers quickly, so the delays were annoying, but not a critical issue.
I'm actually ordering more diapers to stock up, since all indications are that inflation will get MUCH worse before things get better.